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2. BLASIUS, K. R., JOURNAL OF GEOPHYSICAL RESEARCH 78: 4411 (1973).
3. PERSONAL COMMUNICATION
4. Briggs G. A. abstract of paper presented at the third annual meeting of the American Astronomical Society Division of Planetary Sciences (AAS-DPS) Tucson Arizona March (1973).
5. Curran R. J. abstract of paper presented at the third annual meeting of the AAS-DPS Tucson Arizona March (1973).