@Book{Löbell1952,
author  = "Löbell, Frank",
title   = "Integrabilitätsbedingungen in der Theorie der Flächenabbildungen",
year    = "1952",
address = "München",
series  = "Sitzungsberichte",
volume  = "1951,2",
url     = "https://publikationen.badw.de/en/003383660",
}