Annals of the International Geophysical Year v. IV : tables of IGY monthly median ionospheric data edited by W. J. G. Beynon and C. M. Minnis - Oxford Pergamon Press 1961 - 554p. illus - Annals of the International Geophysical Year . ISBN: 1483226328 Subjects--Topical Terms: International Geophysical Year Universal Decimal Class. No.: 550.38 / LEC