Google Scholar indexes research articles and abstracts from most major academic publishers and repositories worldwide, including both free and subscription sources. To look for current coverage of a specific source, search for a sample of their article titles in quotes.

It is not possible to guarantee uninterrupted coverage of any particular source, however, they attempt to be as comprehensive as possible. Articles are indexed from sources all over the web and link to these websites in the search results. If a website becomes unavailable to their search robots or to a large number of web users, it is removed until it becomes available again.