@Book{Voss1921,
author  = "Voss, Aurel",
title   = "Zur Theorie der reziproken Radien",
year    = "1921",
address = "München",
series  = "Sitzungsberichte",
volume  = "1920,11",
url     = "https://publikationen.badw.de/de/003395463",
}