@book{7613,
	author = {International Astronomical Union Colloquium and Donn, B., ed. and International Astronomical Union },
	title = {The study of comets},
	publisher = {National Aeronautics and Space Administration},
	year = {1976},
	series = {NASA SP-393; no. 25},
	address = {Washington},
	note = {Donated by Mrs. Bappu}
}