The Review of Literature (ROL) is a critical part of research that involves identifying, analyzing, and synthesizing existing studies related to a research topic. One of the essential steps in the ROL is determining the location of sources, which involves identifying where and how to find relevant literature.
1. Sources of Literature
Literature for a research study can be located from various sources, including primary, secondary, and tertiary sources.
A. Primary Sources
Definition: Original research, firsthand information, or raw data.
Examples:
Research articles published in peer-reviewed journals.
Theses and dissertations.
Conference papers.
Clinical trial reports.
Government or institutional reports.
B. Secondary Sources
Definition: Summarized or analyzed versions of primary sources.
Examples:
Systematic reviews and meta-analyses.
Books and textbooks.
Review articles in journals.
Reports and policy briefs.
C. Tertiary Sources
Definition: Compiled information from primary and secondary sources.
Examples:
Encyclopedias.
Databases (e.g., Cochrane Library, CINHAL).
Indexes and abstracts.
Bibliographies.
2. Where to Locate Literature?
A. Online Databases
PubMed (Biomedical and healthcare studies)
CINAHL (Cumulative Index to Nursing and Allied Health Literature)
Google Scholar (Academic articles across various disciplines)
Cochrane Library (Systematic reviews and evidence-based research)
ScienceDirect (Scientific and technical research)
Scopus (Multidisciplinary research database)
ProQuest (Theses, dissertations, and research papers)
Medline (Medical and healthcare research)
ERIC (Education Resources Information Center) – For education-related research.
B. Institutional Repositories
University libraries and online research repositories.
Open-access thesis databases (e.g., Shodhganga for Indian theses).
Institutional research centers.
C. Books and Textbooks
Found in university libraries, e-books, and online platforms like:
SpringerLink
Wiley Online Library
Elsevier
OpenStax (Free academic textbooks)
D. Government and International Reports
WHO (World Health Organization)
CDC (Centers for Disease Control and Prevention)
National Health Surveys
Ministry of Health reports
ICMR (Indian Council of Medical Research)
E. Grey Literature
Definition: Research that is not published in commercial journals.
Examples:
Conference proceedings.
White papers.
NGO reports.
Government research findings.
F. Manual Searching and Citation Tracking
Searching reference lists of journal articles.
Identifying seminal research through citation tracking.
Using academic networking platforms like ResearchGate or Academia.edu.
3. How to Select Relevant Literature?
Relevance: Does the source address your research problem?
Credibility: Is the source from a peer-reviewed journal or a recognized institution?
Recency: Prefer literature from the last 5-10 years for updated information.
Comprehensiveness: Covers all key aspects of the research topic.
Objectivity: Avoids bias and presents evidence-based information.
Locating literature is a crucial step in a Review of Literature (ROL). By using online databases, institutional repositories, books, government reports, and grey literature, researchers can ensure a comprehensive and credible literature review.
Sources of Literature for Research
In a Review of Literature (ROL), sources of literature refer to the various places from which information is gathered to support research. These sources provide background knowledge, theoretical foundations, and evidence to justify the study.
Types of Sources in Literature Review
Sources of literature are classified into three main categories: Primary, Secondary, and Tertiary Sources.
1. Primary Sources
These are original, first-hand pieces of information or research. They provide direct evidence and raw data.
Examples of Primary Sources:
Research Articles (Peer-reviewed journals)
Theses and Dissertations
Conference Papers
Clinical Trial Reports
Government and Institutional Reports
Interviews and Case Studies
Official Records (Census, Hospital Data, etc.)
Experimental Studies and Surveys
Where to Find Primary Sources?
PubMed, CINAHL, Medline (For healthcare and nursing research)
Google Scholar, ScienceDirect, Scopus (Multidisciplinary research)
Cochrane Library (Systematic reviews and trials)
University Repositories (Theses & Dissertations)
Government Portals (e.g., WHO, CDC, ICMR)
2. Secondary Sources
These sources analyze, summarize, or interpret primary sources. They do not contain original research but provide an overview of existing studies.
Professional Organization Websites (e.g., American Nurses Association)
Other Important Literature Sources
Apart from traditional sources, researchers also use grey literature and digital sources.
4. Grey Literature
Definition: Research that is not formally published in academic journals.
Examples:
Conference Proceedings
Government and NGO Reports
White Papers
Technical Reports
Working Papers (Preprints)
Hospital or Internal Healthcare Reports
Where to Find Grey Literature?
WHO, CDC, ICMR Reports
UNICEF, UNESCO Publications
Preprint Servers (arXiv, bioRxiv)
Institutional and Organizational Websites
5. Digital and Online Sources
Academic Websites (ResearchGate, Academia.edu)
E-learning Platforms (Coursera, edX for research methodologies)
Google Books & Open Library (Free textbooks)
Social Media & Blogs (Used cautiously for trends, expert opinions)
How to Choose the Best Source?
Reliability: Is the source peer-reviewed, from a reputed institution, or government agency?
Relevance: Does it directly relate to your research problem?
Recency: Prefer sources from the last 5-10 years for updated information.
Credibility: Check the author’s credentials, affiliations, and citations.
Objectivity: Ensure the source is unbiased and based on evidence.
A well-rounded Review of Literature (ROL) includes a mix of Primary, Secondary, and Tertiary sources. Additionally, grey literature and digital sources play a significant role in gathering the most comprehensive and up-to-date information. Researchers must select sources based on credibility, relevance, and reliability to ensure the validity of their study.
Online Search for Literature: CINHAL, COCHRANE, and Other Databases
Introduction
Online literature search is a crucial step in conducting research. It involves using electronic databases to locate scholarly articles, research studies, systematic reviews, and evidence-based practices. Several specialized databases cater to different fields, particularly in healthcare, nursing, and medicine.
1. Online Databases for Literature Search
Below are some of the most widely used databases for literature reviews, particularly in nursing, healthcare, and medical research.
A. CINAHL (Cumulative Index to Nursing and Allied Health Literature)
What is it?
CINAHL is a nursing and allied health research database providing access to journal articles, evidence-based care sheets, clinical trials, and practice guidelines.
Why use it?
It is one of the best sources for nursing education, patient care, and allied health research.
What does it include?
More than 5,000 nursing and allied health journals.
Nursing procedures, best practices, and guidelines.
Evidence-based practice (EBP) resources.
How to access?
Available through EBSCOhost (subscription required).
Many universities provide access via institutional login.
✅ Best for: Nursing students, practitioners, and healthcare researchers.
B. COCHRANE LIBRARY
What is it?
The Cochrane Library is a highly respected database that provides systematic reviews, clinical trials, and evidence-based medical research.
Why use it?
It offers high-quality evidence for clinical decision-making.
Cochrane systematic reviews are widely recognized in evidence-based medicine (EBM).
What does it include?
Cochrane Reviews: Systematic reviews summarizing medical research.
Clinical Trials Database: A registry of ongoing and completed trials.
Cochrane Clinical Answers (CCA): Quick summaries of clinical questions.
✅ Best for: Medical, nursing, and allied health research.
D. Google Scholar
What is it?
A free academic search engine indexing research articles, books, theses, and patents.
Why use it?
Provides a broad search across multiple disciplines.
Finds full-text articles in open-access journals.
Limitations:
Not all articles are peer-reviewed.
Some sources are not always credible.
✅ Best for: Quick searches, interdisciplinary research, and locating open-access articles.
E. Scopus
What is it?
A multidisciplinary database providing research articles, citations, and analytics.
Why use it?
Indexes more than 25,000 peer-reviewed journals.
Offers citation tracking and author profiles.
How to access?
Available via institutional subscriptions.
✅ Best for: High-impact research and citation analysis.
F. Web of Science
What is it?
A premium research database covering medical, health, and social sciences.
Why use it?
High-quality peer-reviewed articles.
Citation tracking and impact factor data.
How to access?
Requires institutional subscription.
✅ Best for: High-quality, peer-reviewed research.
G. ProQuest Dissertations & Theses Global
What is it?
A database that contains theses and dissertations from universities worldwide.
Why use it?
Great for finding original research work.
Provides unpublished studies and doctoral research.
How to access?
Available via university subscriptions.
✅ Best for: Reviewing unpublished research and dissertations.
H. ERIC (Education Resources Information Center)
What is it?
A database focused on educational research.
Why use it?
Provides articles, books, reports, and conference papers on teaching and education.
How to access?
Free at eric.ed.gov.
✅ Best for: Nursing education, teacher training, and pedagogy research.
2. Tips for Effective Online Literature Search
To conduct an effective and systematic literature search, follow these strategies:
A. Use Boolean Operators
AND – Narrows the search (e.g., nursing AND patient care).
OR – Expands the search (e.g., diabetes OR hypertension).
NOT – Excludes terms (e.g., cancer NOT lung).
B. Use Filters and Advanced Search
Year Filters – Choose articles from the last 5-10 years for updated data.
Full-text Access – Limit results to open-access articles.
Subject Areas – Select nursing, healthcare, or medicine.
C. Search Using Keywords and Phrases
Use specific and relevant keywords related to your topic.
Try synonyms and alternative terms.
Example: Searching for the impact of nurse staffing on patient outcomes:
Keyword Search:Nurse staffing AND patient care quality
Alternative Search:Nursing workload AND patient outcomes
D. Check Citation Tracking
Look at highly cited articles for influential research.
Use Google Scholar’s “Cited By” feature to find newer studies.
E. Access Institutional Subscriptions
Universities and medical institutions provide free access to paid databases.
Check your library’s remote login access.
A successful literature review requires using reliable online databases like CINAHL, Cochrane Library, PubMed, and Scopus. Researchers should use Boolean operators, filters, and keyword strategies to refine their search. Combining multiple sources ensures comprehensive and high-quality research findings.
✅ For Nursing & Healthcare Research:
CINAHL (Nursing & Allied Health)
Cochrane Library (Systematic Reviews & EBP)
PubMed (Biomedical Research)
Scopus/Web of Science (High-Impact Journals)
Online Search for Literature: CINHAL, COCHRANE, and Other Databases
Introduction
Online literature search is a crucial step in conducting research. It involves using electronic databases to locate scholarly articles, research studies, systematic reviews, and evidence-based practices. Several specialized databases cater to different fields, particularly in healthcare, nursing, and medicine.
1. Online Databases for Literature Search
Below are some of the most widely used databases for literature reviews, particularly in nursing, healthcare, and medical research.
A. CINAHL (Cumulative Index to Nursing and Allied Health Literature)
What is it?
CINAHL is a nursing and allied health research database providing access to journal articles, evidence-based care sheets, clinical trials, and practice guidelines.
Why use it?
It is one of the best sources for nursing education, patient care, and allied health research.
What does it include?
More than 5,000 nursing and allied health journals.
Nursing procedures, best practices, and guidelines.
Evidence-based practice (EBP) resources.
How to access?
Available through EBSCOhost (subscription required).
Many universities provide access via institutional login.
✅ Best for: Nursing students, practitioners, and healthcare researchers.
B. COCHRANE LIBRARY
What is it?
The Cochrane Library is a highly respected database that provides systematic reviews, clinical trials, and evidence-based medical research.
Why use it?
It offers high-quality evidence for clinical decision-making.
Cochrane systematic reviews are widely recognized in evidence-based medicine (EBM).
What does it include?
Cochrane Reviews: Systematic reviews summarizing medical research.
Clinical Trials Database: A registry of ongoing and completed trials.
Cochrane Clinical Answers (CCA): Quick summaries of clinical questions.
✅ Best for: Medical, nursing, and allied health research.
D. Google Scholar
What is it?
A free academic search engine indexing research articles, books, theses, and patents.
Why use it?
Provides a broad search across multiple disciplines.
Finds full-text articles in open-access journals.
Limitations:
Not all articles are peer-reviewed.
Some sources are not always credible.
✅ Best for: Quick searches, interdisciplinary research, and locating open-access articles.
E. Scopus
What is it?
A multidisciplinary database providing research articles, citations, and analytics.
Why use it?
Indexes more than 25,000 peer-reviewed journals.
Offers citation tracking and author profiles.
How to access?
Available via institutional subscriptions.
✅ Best for: High-impact research and citation analysis.
F. Web of Science
What is it?
A premium research database covering medical, health, and social sciences.
Why use it?
High-quality peer-reviewed articles.
Citation tracking and impact factor data.
How to access?
Requires institutional subscription.
✅ Best for: High-quality, peer-reviewed research.
G. ProQuest Dissertations & Theses Global
What is it?
A database that contains theses and dissertations from universities worldwide.
Why use it?
Great for finding original research work.
Provides unpublished studies and doctoral research.
How to access?
Available via university subscriptions.
✅ Best for: Reviewing unpublished research and dissertations.
H. ERIC (Education Resources Information Center)
What is it?
A database focused on educational research.
Why use it?
Provides articles, books, reports, and conference papers on teaching and education.
How to access?
Free at eric.ed.gov.
✅ Best for: Nursing education, teacher training, and pedagogy research.
2. Tips for Effective Online Literature Search
To conduct an effective and systematic literature search, follow these strategies:
A. Use Boolean Operators
AND – Narrows the search (e.g., nursing AND patient care).
OR – Expands the search (e.g., diabetes OR hypertension).
NOT – Excludes terms (e.g., cancer NOT lung).
B. Use Filters and Advanced Search
Year Filters – Choose articles from the last 5-10 years for updated data.
Full-text Access – Limit results to open-access articles.
Subject Areas – Select nursing, healthcare, or medicine.
C. Search Using Keywords and Phrases
Use specific and relevant keywords related to your topic.
Try synonyms and alternative terms.
Example: Searching for the impact of nurse staffing on patient outcomes:
Keyword Search:Nurse staffing AND patient care quality
Alternative Search:Nursing workload AND patient outcomes
D. Check Citation Tracking
Look at highly cited articles for influential research.
Use Google Scholar’s “Cited By” feature to find newer studies.
E. Access Institutional Subscribe
A successful literature review requires using reliable online databases like CINAHL, Cochrane Library, PubMed, and Scopus. Researchers should use Boolean operators, filters, and keyword strategies to refine their search. Combining multiple sources ensures comprehensive and high-quality research findings.
✅ For Nursing & Healthcare Research:
CINAHL (Nursing & Allied Health)
Cochrane Library (Systematic Reviews & EBP)
PubMed (Biomedical Research)
Scopus/Web of Science (High-Impact J
Purposes of Review of Literature (ROL)
A Review of Literature (ROL) serves multiple purposes in research. It helps to identify gaps, provide background information, justify the study, and guide research methodology. Below are the key purposes:
1. Identifying Research Gaps
Helps to determine what is already known and what is missing in existing studies.
Example: If studies have examined nurse-patient ratios in urban hospitals but not in rural settings, this gap can justify a new study.
2. Understanding the Background of the Topic
Provides historical context and evolution of concepts in a research area.
Helps to define key terms, theories, and concepts relevant to the study.
3. Justifying the Research Problem
Strengthens the need for the study by showing why the research is important.
Supports the argument that the problem is significant and worth investigating.
4. Avoiding Duplication
Ensures that the research is original and not a repetition of past studies.
Helps refine the study to add new knowledge rather than repeat existing findings.
5. Developing Theoretical and Conceptual Framework
Helps in selecting an appropriate theory or model to explain relationships in research.
Example: A study on nurse burnout may be guided by Maslach’s Burnout Theory.
6. Supporting Research Objectives and Hypotheses
Provides evidence to formulate research questions and hypotheses.
Helps in making valid predictions based on previous findings.
7. Guiding Methodology Selection
Helps in choosing the best research design, data collection methods, and tools.
Example: If past studies used surveys, the researcher may decide whether to follow the same or use interviews for deeper insights.
8. Providing a Basis for Data Interpretation
Helps compare new findings with previous research results.
Supports discussion and conclusion by relating new evidence to past studies.
9. Identifying Reliable Sources and Key Researchers
Helps locate seminal research (pioneering studies) and current trends.
Identifies key authors, institutions, and journals in the field.
10. Supporting Evidence-Based Practice (EBP)
In nursing and healthcare research, literature review provides scientific evidence to improve clinical practices and patient care.
Example: A systematic review on hand hygiene compliance helps develop hospital policies.
The Review of Literature (ROL) is a critical step in research. It identifies gaps, provides justification, supports methodology, and strengthens findings. A well-conducted literature review ensures that research is relevant, original, and evidence-based.
Methods of Review of Literature (ROL)
A Review of Literature (ROL) can be conducted using various methods depending on the research purpose, depth, and scope. Below are the main methods used in literature reviews:
1. Narrative Review (Traditional Review)
Definition:
A qualitative summary of existing literature that provides a broad overview of a research topic.
Characteristics:
✅ Descriptive & Subjective – No strict systematic approach. ✅ Summarizes and synthesizes key studies. ✅ Identifies trends, theories, and gaps in literature. ✅ Often used in theoretical research and conceptual studies.
Example:
A review discussing the history of evidence-based nursing without systematic selection of studies.
2. Systematic Review
Definition:
A structured and comprehensive review that follows a pre-defined method to collect, evaluate, and synthesize relevant studies.
Characteristics:
✅ Clearly defined research question. ✅ Uses inclusion/exclusion criteria for selecting studies. ✅ Follows a systematic data extraction process. ✅ Often quantitative, focusing on statistical findings.
Steps in Systematic Review:
Define the research question (e.g., using PICO framework).
Apply inclusion/exclusion criteria to filter relevant studies.
Extract key data (sample size, outcomes, limitations).
Analyze and synthesize findings systematically.
Example:
A systematic review on the effectiveness of hand hygiene interventions in reducing hospital infections.
✅ Best for:Evidence-based practice (EBP), healthcare research, and policy-making.
3. Meta-Analysis
Definition:
A quantitative technique that combines statistical data from multiple studies to produce a pooled effect size.
Characteristics:
✅ Statistical analysis of combined study results. ✅ Uses forest plots to visualize findings. ✅ Focuses on effect size & significance levels. ✅ Requires studies with similar methodologies.
Example:
A meta-analysis of 20 randomized controlled trials (RCTs) measuring the effectiveness of yoga in reducing anxiety among patients.
✅ Best for:Comparing multiple studies with statistical consistency.
4. Meta-Synthesis
Definition:
A qualitative review method that integrates findings from different qualitative studies.
Characteristics:
✅ Synthesizes themes from qualitative research. ✅ Uses interpretative analysis instead of statistics. ✅ Generates new theories or frameworks.
Example:
A meta-synthesis on the lived experiences of cancer survivors regarding pain management strategies.
✅ Best for:Exploring subjective experiences in healthcare and nursing.
5. Scoping Review
Definition:
A review that maps existing literature on a broad topic without assessing study quality.
Characteristics:
✅ Exploratory – Helps understand research trends. ✅ Identifies knowledge gaps and future research areas. ✅ More inclusive than systematic reviews.
Example:
A scoping review identifying the current research trends on digital health interventions in nursing practice.
✅ Best for:Exploring emerging research areas.
6. Integrative Review
Definition:
A comprehensive review that includes both qualitative and quantitative studies.
Characteristics:
✅ Uses a broad range of study designs. ✅ Summarizes different types of evidence (RCTs, case studies, observational studies). ✅ Bridges theoretical and empirical research.
Example:
An integrative review examining the impact of mindfulness-based interventions on stress reduction in nurses, including clinical trials and qualitative feedback.
✅ Best for:Healthcare and interdisciplinary research.
7. Critical Review
Definition:
A review that analyzes and critiques existing research, questioning its validity and significance.
Characteristics:
✅ Critically evaluates the strengths and weaknesses of studies. ✅ Identifies biases, limitations, and inconsistencies in research. ✅ Often used in philosophy, social sciences, and policy analysis.
Example:
A critical review of healthcare disparities in rural and urban settings, questioning policy effectiveness.
✅ Best for:Theoretical and conceptual debates.
8. Rapid Review
Definition:
A time-efficient version of a systematic review that focuses on summarizing key evidence quickly.
Characteristics:
✅ Uses simplified methods for searching and selecting studies. ✅ Often used in policy-making and urgent decision-making. ✅ May lack the rigor of a full systematic review.
Example:
A rapid review of COVID-19 vaccination strategies in different countries.
✅ Best for:Healthcare policies and emergency decision-making.
Comparison of Review Methods
Method
Approach
Data Type
Strengths
Best For
Narrative Review
Descriptive
Qualitative
Broad overview
Theoretical research
Systematic Review
Structured
Quantitative
High-quality evidence
Evidence-based practice
Meta-Analysis
Statistical
Quantitative
Pooled effect size
Comparing multiple studies
Meta-Synthesis
Thematic
Qualitative
Generates new insights
Subjective experiences
Scoping Review
Exploratory
Mixed
Identifies research gaps
Emerging research areas
Integrative Review
Comprehensive
Mixed
Bridges different types of evidence
Interdisciplinary research
Critical Review
Analytical
Mixed
Evaluates biases and weaknesses
Policy and theoretical debates
Rapid Review
Quick summary
Mixed
Fast decision-making
Policy updates
Choosing the right method of literature review depends on the research question, study design, and available time.
For evidence-based nursing, a systematic review or meta-analysis is best.
For broad topic exploration, a scoping review works well.
For qualitative insights, a meta-synthesis is preferred.