"What if you could search the research output of hundreds of institutions in one place, gaining access to some of the most important research being done on any number of fields of interest?
Luckily, you can. I know of two directories that allow you to not only find a specific institutional repository, but also search the content of all repositories they have registered. Namely ROAR, the Registry of Open Access Repositories and OpenDOAR, the Directory of Open Access Repositories. Both utilize a Google custom search engine that allows you to search across the repositories for specific terms."