@Book{Löbell1955,
author  = "Löbell, Frank",
title   = "Differentialformen in der Theorie der Flächenabbildungen",
year    = "1955",
address = "München",
series  = "Sitzungsberichte",
volume  = "1954,9",
url     = "https://publikationen.badw.de/de/003383794",
}