Ingo. Libretto. German Opera. Public domain libretto, Library of Congress

nach dem gleichnamigen Roman Gustav Freytags von M.F. [i.e. Martha Friedemann] ; in Musik gesetzt von Philipp Rüfer. (statement of responsibility)
U.S. RISM Libretto Project.
Price on title page: 50 Pfg.; legal notices--title page and verso; "Als Manuscript gedruckt"--verso of title page; "Druck von C.G. Röder in Leipzig"--p. 40.
Libretto by Martha Friedemann--Stieger. Opernlexikon.
Performers' names not given.