@Book{Haupt1949,
author  = "Haupt, Otto",
title   = "Die Paare ähnlicher Kegelschnitte in Kegelschnittbüscheln",
year    = "1949",
address = "München",
series  = "Sitzungsberichte",
volume  = "1947,12.",
url     = "https://publikationen.badw.de/en/003395832",
}