IV. Score in a series:  Use the same style as a "Book in a Series."
(Note: DO NOT underline or italicize the series title)  following MLA 8
 
e. With a parallel title:

Gassman, Florian Leopold.  Zwei Streichtrios = Two String Trios. Edited by Wolfgang Sawodny, Bärenreiter, 1988.  Hortus Musicus, 247.  Parts.