The remains of the music collection that once belonged to the court of Anhalt-Zerbst has been dispersed (and much of it possibly lost forever). There are two main deposits, however: some forty pieces from the time of Fasch's tenure survive at the Landeshauptarchiv Sachsen-Anhalt (currently in the Dessau archives), while a dozen or so are in the library of the Musicology Department of the University of Halle/Saale.
The following is an updated version of a paper catalogue I printed in 1994, and lists the materials in Dessau.
A1-A15 Cantatas attributed to Johann Friedrich Fasch
A16-A26 Masses attributed to Johann Friedrich Fasch
A27-A32 Attributed church music