Semi-empirical models of the quiet ionosphere. Koen, M. A. ; Barajshchuk, S. N. ; Burenkov, S. N. ; Kazmirov, A. D. ; Khazanov, D. V. Abstract Publication: Ionosfernye Issledovaniia Pub Date: 1987 Bibcode: 1987IonIs..42...10K Keywords: Earth Ionosphere