Unfortunately there are few academic or reference books available on the topic of filk music. However, an excellent resource is former BGSU graduate student Solomon H. Davidoff's M.A. thesis on the topic:
Additional information on filk may be found in books about science fiction, fan fiction, or fan communities. Try these items in the collection to begin a further search:
The MLBSSA at Bowling Green State University also has a rich collection of filk music fanzines, magazines, and journals. Some of these contain articles or commentary, but most are collections of lyrics or songs. The collections contain songs by particular filkers, songs on certain topics, or tunes that were performed at particular conventions or gatherings.
These can be found by searching for the subject "Science Fiction -- Songs and music" -- Periodicals" or by searching for the subject "Filk music" and limiting your results to periodicals.
Many of the magazines and fanzines above feature new lyrics designed to be sung to familiar tunes and, occasionally, music notation for filk tunes. MLBSSA also has a handful of filk scores, which you can find by searching for the subject "Science Fiction -- Songs and Music" and limiting your results to musical score.
When searching for a specific score, recording, book or DVD, an essential step any music library user must take is to designate the Material Type in the Library Catalog's Advanced Search menu:
Using this feature allows you narrow your search to ONE TYPE of item so you can browse through broad searches more easily, or improve the accuracy of refined search results.