Epstein S.  1956.  Variations of the O18/O16 Ratios of Fresh Waters and Ice. Nuclear Processes in Geologic Settings. 19:20-28.

Sharp RP, Epstein S, Vidziunas I.  1960.  Oxygen-Isotope Ratios in the Blue Glacier, Olympic Mountains, Washington, U. S. A.. Journal of Geophysical Research. 65:4043-4060.