@Book{Haupt1963,
author  = "Haupt, Otto",
title   = "Zur Geometrie in topologisch ebenen hyperbolischen Ebenen",
year    = "1963",
address = "München",
series  = "Sitzungsberichte",
volume  = "1962,10",
url     = "https://publikationen.badw.de/de/003384091",
}