TY - RPRT TI - The ancient oxygen exosphere of Mars: Implications for atmosphere evolution AU - Zhang, M. H. G. AU - Luhmann, J. G. AU - Nagy, A. F. AU - Bougher, S. W. PY - 1992 UR - https://ntrs.nasa.gov/citations/19920019837 ID - 19920019837 ER -