6 books in series

Perry Rhodan Extra

Perry Rhodan Extra is a 6-book series with 6 primary works first released in 2004 with contributions by Robert Feldhoff, Wim Vandemaan, Achim Mehnert, Hubert Haensel, Frank Borsch, and Marc A. Herren.

Der Sternenbastard
Das Andromeda-Monument
BARDIOCS Null
Die Stardust-Maschine
Das Stardust-Attentat
Gesänge der NACHT