@Book{Steuerwald1949,
author  = "Steuerwald, Rudolf",
title   = "Über die Kongruenz an-1 [Kongruenzzeichen] 1 (mod n)",
year    = "1949",
address = "München",
series  = "Sitzungsberichte",
volume  = "1948,4",
url     = "https://publikationen.badw.de/en/003383584",
}