@book {9783170232440, 
	title = "Kaiser Friedrich II. (1194-1250)",
	author = "Houben, Hubert",
	isbn = "9783170232440",
	year = "2008",
	edition = "1",
	keywords = "Friedrich Barbarossa, Kaiser Friedrich II., Roger von Sizilien",
	url = "http://www.content-select.com/index.php?id=bib_view&ean=9783170232440",
	url = "https://content-select.com/de/portal/media/view/517a535a-40fc-480c-ab01-1b855dbbeaba",
	publisher = "W. Kohlhammer Verlag",
	language = "ger",
}