@Book{Lettenmeyer1935,
author  = "Lettenmeyer, Fritz",
title   = "Gleichungen unendlich hohen Grades in zwei Variabeln",
year    = "1935",
address = "München",
series  = "Sitzungsberichte",
volume  = "1935,18",
url     = "https://publikationen.badw.de/en/020295796",
}