@Book{Freyberg1837,
author  = "Freyberg, Maximilian Prokop von",
title   = "Beurkundete Geschichte Herzog Ludwigs des Brandenburgers",
year    = "1837",
address = "München",
series  = "Abhandlungen",
volume  = "2,1",
url     = "https://publikationen.badw.de/de/003189250",
}