@Book{Sauer1929,
author  = "Sauer, Robert",
title   = "Herleitung differentialgeometrischer Flächeneigenschaften aus Sehnen-Dreiecksflachen",
year    = "1929",
address = "München",
series  = "Sitzungsberichte",
volume  = "1929,16",
url     = "https://publikationen.badw.de/en/003383295",
}