@Book{buch,
	author = {Peter Ostmann},
	title = {B-Aufgabenvorlage},
	publisher = {Peter Ostmann},
	year = {2017}
}

@ONLINE{online,
	author = {Peter Ostmann,
	title = {Peter Ostmann - Ostmann.it},
	url = {http://www.ostmann.it},
	}}
}