Organ literature : a comprehensive survey / by Corliss Richard Arnold. 2 vols.
Metuchen, NJ : Scarecrow Press, 1995
MUSIC Ref ML600.A76 1995
Catalogue of music for organ and instruments / James H. Laster
Lanham, Md. : Scarecrow Press, 2005
MUSIC Ref ML128.O6 L34 2005
Organ and harpsichord music by women composers : an annotated catalog / compiled by Adel Heinrich
New York : Greenwood Press, 1991
MUSIC Ref ML128.O6 O73 1991
Organ music in print / edited by Thomas R. Nardone
Philadelphia : MusicData, 1975, and supplements to 1997
MUSIC Ref ML128.O6 N37
Repertorium Orgelmusik : Komponisten, Werke, Editionen, 1150-2000, 57 Länder : eine Auswahl = A bio-bibliographical index of organ music : composers, works, editions, 1150-2000, 57 countries : a selection / Klaus Beckmann. 2 vols.
Mainz ; New York : Schott, 2001-
MUSIC Ref ML128.O6 B4 2001
The American organist, v. 13 (1979)- ML1.M787x
The tracker : journal of the Organ Historical Society, v. 28 (1984)- ML1.T733x
Choir & organ, 1993- Online
Clavier, v. 1 (1962) - v. 47 (2008) ML1.C79
Clavier companion, v. 1 (2009)- ML1.C792
The organ, no. 85 (1942)- ML5.O7
...and many more. Search for the subject "Organ (Musical instrument)--Periodicals" in the catalog.
M - Scores
M6-19--Solo organ music
M180-195--Music for two organs or organ and one other instrument
M1005-1006, M1108-1109--Organ with orchestra and string orchestra (includes full scores and solos with piano arrangements)
ML - Music Literature
ML128.O6--Organ music: Bibliography
ML549-649--Books about the organ
MT - Instruction and Study
MT180-208--Methods, etudes, orchestra studies, etc.
Organ music
Suites (Organ)
Concertos (Organ)
Concertos (Organ with string orchestra)
Organ with orchestra
...and there are lots more. Do a subject search for "organ" or for "organ (musical instrument)" and see the different subject headings that begin with "organ."
Organ music--Bibliography
Organ music--Discography
Organ (Musical instrument)--History
Organists
... and lots more. Search "organ" in the library catalog and find more than 1700 recordings and more than 3000 scores.