@Book{Baldus1932,
author  = "Baldus, Richard",
title   = "Zur Theorie der Büschel von Flächen 2. Ordnung",
year    = "1932",
address = "München",
series  = "Sitzungsberichte",
volume  = "1931,8",
url     = "https://publikationen.badw.de/en/003383347",
}