by Simonelli, D P, Pollack, J B, McKay, C P, Reynolds, R T, Summers, A L
Published in Icarus (New York, N.Y. 1962) (01.11.1989)

by Lehr, H.B., Berggren, R.B., Summers, A.L., Lotke, P.A.
Published in Cryobiology (01.11.1964)