Google late Wednesday rolled out a beta search tool designed for academics and other researchers digging through peer-reviewed papers, abstracts, and theses.

Google Scholar, which unlike the standard Google doesn't post ads on result pages, searches a subset of the San Francisco-based search giant's 8-billion page index, as well as new entries that Google added after getting publishers to let its spider crawl behind subscription walls.

In other cases, results that Scholar returns might not even be online, but has only been referenced in an online document.

"A large fraction of scholarly literature is still offline," said Google in a FAQ that outlines the new search tool's features. "Until these papers are available online, citation-only results help researchers find as much relevant information as possible."

In such cases, a Library Search and/or a Web Search link shows next to the book's or paper's title. The former uses the Open WorldCat program to locate a nearby library with the work, while Web Search searches the larger index for other, non-scholarly references.

That's why, said one search expert, Google Scholar may bring people back to libraries for research.

"The material may have already been available, but if the public didn't realize this, it remained invisible," said Danny Sullivan, who runs the site SearchEngineWatch.com. "More and more, the public continues to turn to search engines to access all types of information. But this move, ironically, may raise more awareness and use of libraries as an important offline research resource."