Grey literature

Grey literature is research produced outside traditional commercial publishing. Examples of grey literature: conference abstracts and proceedings, poster presentations, technical reports, government reports, datasets, thesis/dissertations, newsletters, lab notes, registries, etc. 

 

ClinicalTrials.gov
ClinicalTrials.gov is a registry and results database of publicly and privately supported clinical studies of human participants conducted around the world.

European Union Clinical Trials Register
The EU Clinical Trials Register contains information on interventional clinical trials on medicines conducted in the European Union (EU).

ISRCTN registry
The ISRCTN registry is a primary clinical trial registry recognised by WHO and ICMJE that accepts all clinical research studies (whether proposed, ongoing or completed), providing content validation and curation and the unique identification number necessary for publication.

WHO International Clinical Trials Registry Platform (ICTRP)
The main aim of the WHO ICTRP is to facilitate the prospective registration of the WHO Trial Registration Data Set on all clinical trials, and the public accessibility of that information.
 

Conference Proceedings Citation Index (part of Web of Science Core Collection)

Other databases such as Embase and PsycINFO include conference proceedings and papers. You can also search individual conference proceedings to locate relevant papers.

Contact company for complete trial data

CADTH (Canadian Agency for Drugs and Technologies in Health)
CADTH is a Canadian independent, not-for-profit organization responsible for providing health care decision-makers with objective evidence.

European Medicines Agency
The European Medicines Agency (EMA) is a decentralised agency of the European Union (EU), located in London. It began operating in 1995. The Agency is responsible for the scientific evaluation, supervision and safety monitoring of medicines in the EU.

Devices@FDA 
Devices@FDA is a catalog of cleared and approved medical device information from the United States Food and Drug Administration (FDA). It includes links to the device summary information, manufacturer, approval date, user instructions, and other consumer information.

Drugs@FDA
Information about FDA-approved brand name and generic prescription and over-the-counter human drugs and biological therapeutic products. Drugs@FDA includes most of the drug products approved since 1939.
 

Researchers may decide to search Google Scholar for studies but may sometimes limit to a certain number of results such as the first 100 or 200. 

Google Scholar searches may retrieve grey literature not indexed in academic databases. Keep in mind that Google Scholar is a search engine not a bibliographic database. 

Google Scholar has an “Advanced Search” which can help focus on the vast number of results. Click on the menu icon in the top left corner to access.