533.6
M61	Methods of Measurements and Results of Lower Ionosphere Structure [Текст] : Proceedings of Symposium held in Constance, F.R.G. 23 - 26 May 1973 / Rawer, K ( edit.) ;The Committee on Space Research-COSPAR:"Deutsche Forschungsgemeinschaft" of the Federal Republic of Germany. — Berlin : Academie-Verlag, 1974. — 462 s.