Tappen, C.M., Webster, J.D., Mandeville, C.W., and Roderick, David, 2009, Petrology and geochemistry of ca. 2100-1000 a.B.P. magmas of Augustine volcano, Alaska, based on analysis of prehistoric pumiceous tephra: Journal of Volcanology and Geothermal Research, v. 183, n. 1/2, p. 42-62, doi: 10.1016/j.jvolgeores.2009.03.007 .