@Book{Sommerfeld1918,
author  = "Sommerfeld, Arnold",
title   = "Über die Feinstruktur der K-beta-Linie",
year    = "1918",
address = "München",
series  = "Sitzungsberichte",
volume  = "1918,14",
url     = "https://publikationen.badw.de/de/003399182",
}