@Book{Koecher1968,
author  = "Koecher, Max",
title   = "Eine Äquivalenzrelation in Ringen",
year    = "1968",
address = "München",
series  = "Sitzungsberichte",
volume  = "1967,6",
url     = "https://publikationen.badw.de/en/003384205",
}