Mullineaux, Donal R., Thomas C. Nichols, and Robert A. Speirer. A Zone of Montmorillonitic Weathered Clay in Pleistocene Deposits at Seattle, Washington In U. S. Geological Survey Professional Paper. Vol. 501-D. Department of the Interior, 1964.

Volk, H. R., and H. E. Rondeel. "Zur Gliederung des Jungtertiars Im Becken von Vera, Sudostspanien." Geologie en Mijnbouw 43 (1964): 310-315.

Bramlette, M. N., and E. Posnjak. "Zeolitic Alteration of Pyroclastics." American Mineralogist 18 (1933): 167-171.