@Book{Mayer1978,
author  = "Mayer, Hans Eberhard",
title   = "Das Siegelwesen in den Kreuzfahrerstaaten",
year    = "1978",
address = "München",
series  = "Abhandlungen",
volume  = "83",
url     = "https://publikationen.badw.de/en/003298168",
}