@book{51789,
	author = {Havel, I.M. and Koubek, V.},
	title = {Mathematical foundations of computer science 1992: 17 International symposium,Prague,Czechoslovakia Aug.24-28, 1992},
	publisher = {Springer-Verlag},
	year = {1992},
	series = {Lecture notes in computer science 629},
	address = {Berlin}
}