@inbook { kerres_potenzial,
	title = {Potenziale von Web 2.0 nutzen},
	booktitle = {Handbuch E-Learning},
	year = {2006},
	publisher = {DWD-Verlag},
	organization = {DWD-Verlag},
	address = {M{\"u}nchen},
	author = {Michael Kerres},
	editor = {Hohenstein, A. and Karl Wilbers}
}
@inbook { petschenka_lerna,
	title = {Lernaufgaben beim E-Learning},
	booktitle = {Handbuch E-Learning},
	volume = {Kap. 4.19},
	year = {2004},
	publisher = {Wolters-Klouwer},
	organization = {Wolters-Klouwer},
	address = {K{\"o}ln},
	author = {Petschenka, Anke and Nadine Ojstersek and Michael Kerres},
	editor = {Hohenstein, A. and Karl Wilbers}
}
