@book{38031,
	author = {Klee, Victor and Wagon, Stan.},
	title = {Old and new unsolved problems in plane geometry and number theory},
	publisher = {The Mathematical Association of America},
	year = {1991.},
	series = {Dolciani mathematical expositions},
	address = {Washington, D.C.},
	note = {Borrar en julio 1993.}
}