@Book{Föppl1941,
author  = "Föppl, Ludwig",
title   = "Die unendliche Halbebene bei beliebiger Randbelastung",
year    = "1941",
address = "München",
series  = "Sitzungsberichte",
volume  = "1941,6",
url     = "https://publikationen.badw.de/en/003399378",
}