@book{9178,
	author = {Symposium on Combinatorics and Graph Theory, Indian Statistical Instt., Calcutta, Feb. 25-29, 1980 and Rao, S. B.},
	title = {Combinatorics and graph theory; proceedings},
	publisher = {Springer-Verlag,},
	year = {1981},
	address = {Berlin:}
}