@MASTERSTHESIS{foerster1996,
	AUTHOR = "Alexander F{\"o}rster",
	TITLE = "Eigenschafte graphischer DOL-Systeme",
	SCHOOL = "Freie Universit{\"a}t Berlin",
	YEAR = {1996},
	MONTH = {July},
	NOTE = {(in german)},
	PS = {http://www.idsia.ch/~alexander/publications/1996/1/diplom.ps}
}