@book{20786,
	author = {Boltyanskii, V. G. and Efremovich, V. A. and Efremovich, V. A. ;Jt. auth.},
	title = {Intuitive combinatorial topology},
	publisher = {Springer-Verlag},
	year = {2001},
	series = {Universitext},
	address = {New York}
}