Developing a systematic approach to finding grey literature for academic purposes can be difficult. Unlike scholarly journals that are often available in electronic formats, grey literature databases will be all over the map in terms of formats and accessibility. You should prepare any search terms you will use, identify the most applicable ones, and record the sources as you search. If you have a research question, use it to guide where you look for the sources you're going to search. There are also many grey literature databases that specialize in cataloging grey literature:

Type	Database	Notes
General	GreySource	GreySource provides links to repositories of grey literature from around the world, categorized by topic.
Conference abstracts	Embase	Alternatively, look for professional organizations that hold conferences where researchers might be presenting work related to the subject you're looking for. Search for these conference abstracts on the organization's website. If you'd like to look at conference proceedings that might not be online, contact the organization's boards.
Medical	Grey Matters	Grey Matters is a practical tool to help you when searching for health-related grey literature. It contains a free checklist to help you build a system for your search.
Scientific	Science.gov, WorldWideScience.org	Find scientific information collated by US government agencies at Science.gov. Or, if you want to expand your search beyond the US, WorldWideScience.org allows you to search archives of scientific information across different parts of the world simultaneously.
Governmental	Policy Archive	Policy Archive is a digital library that provides access to US Government policy documents.
Academic	BASE	Search over 210 million documents at Bielefeld Academic Search Engine (BASE) or use some of these free resources for researchers.
Clinical Trials	ClinicalTrials.gov	Privately and publicly funded clinical studies from around the world.
Research papers	CORE	CORE holds the world’s largest collection of open-access research papers.
Theses and dissertations	NDLTD, Google Scholar	You can find over 5 million dissertations at the Networked Digital Library of Theses and Dissertations (NDLTD). Google Scholar can also help you search dissertations and theses in institutional repositories.
European	Open Grey	Open Grey provides bibliographical references to over 700,000 pieces of grey literature produced in Europe, allowing you to export records and locate documents.