The Baseball Index
"The Baseball Index (TBI) is a free catalog to baseball literature. It encompasses books, magazine articles, programs, pamphlets, films, recordings, songs, poems, cartoons, advertising, or anything else that may be of interest to the baseball fan or researcher. It is an ongoing project of the Bibliography Committee of the Society for American Baseball Research (SABR) to catalog the entirety of baseball literature, from the earliest references to the present day. TBI is the creation of volunteers. Their hours of work and financial contributions have made your TBI research possible.
Remember, TBI is an index to baseball literature. It is a guide to what has been written about baseball subjects. It does not include the full-text of the sources referenced."