@Book{Perron1958,
author  = "Perron, Oskar",
title   = "Über zwei Kettenbrüche von H. S. Wall",
year    = "1958",
address = "München",
series  = "Sitzungsberichte",
volume  = "1957,1",
url     = "https://publikationen.badw.de/de/003383950",
}