Grey Literature: Overview

The term Grey Literature has been given many definitions

• Everything published outside of books and journal articles
• publications that are not acquired or located through commercial vendors
• documents that cannot be identified using an index or electronic database

The list of the different types or formats of Grey Literature is extensive.

Examples of grey literature are

• Bibliographies
• Government Documents
• Posters
• Standards
• Online Repositories
• Conference proceedings
• Clinical trials
• Websites
• Social media

Unsure if the format you are currently reviewing is classified as Grey Literature.

Refer to GreyNet's list of document types for more formats

Depending on your research or information topic, it may not be necessary to search a wide range of resources 

Grey Literature should be considered for inclusion in some of the following examples

• A Systematic review that requires a comprehensive search of ALL available information on the topic
• A new concept or condition with no published studies in peer review journals
• Looking for other grey literature for updating local policies and procedures
• Offers diverse sources of information eg. investigating local community projects
• Searching for unpublished studies on a new drug for clinical trials research

The AACODS checklist is designed to enable evaluation and critical appraisal of grey literature.

The checklist is based on six key criteria

A  - Authority

A  - Accuracy

C -  Coverage

O - Objectivity

D - Date

S - Significance

Cabrini Discovery Search -

The discovery layer searches across other websites and online resources that are open access as well as subscribed ebooks and ejournals.

The following comprehensive checklist is recommended particularly for systematic review research.

Grey Matters : a practical tool for searching health-related grey literature. Ottawa : CADTH; 2022