@book{9731,
	author = {Janssen, Arnold},
	title = {Permissible translations of semi group folds; doctoral dissertation of Dortmund Univ.},
	publisher = {Dortmund University},
	year = {1979},
	address = {Dortmund},
	note = {Original German title is" Zulassige translationen von faltungshalbgruppen"}
}