Drum samples

Richter, D. H., Duffield, W. A., Sawyer, D. A., Schmoll, H. R., and Ratte, J. C., 1994, Geologic map of the Gulkana A-1 Quadrangle, south-central Alaska: U.S. Geological Survey Geological Quadrangle Map GQ 1728, unpaged, 1 sheet, scale 1:63,360.

Richter, D.H., Moll-Stalcup, E.J., Miller, T.P., Lanphere, M.A., Dalrymple, G.B., and Smith, R.L., 1994, Eruptive history and petrology of Mount Drum volcano, Wrangell Mountains, Alaska: Bulletin of Volcanology, v. 56, n. 1, p. 29-46.

Richter, D. H., Smith, R. L., Yehle, L. A., and Miller, T. P., 1979, Geologic map of the Gulkana A-2 quadrangle, Alaska: U.S. Geological Survey Geological Quadrangle Map GQ 1520, unpaged, 1 plate, scale 1:63,360.

Preece, S. J., 1997, Geochemical variation in the less than 5 Ma Wrangell Volcanic Field, Alaska, with an emphasis on the Skookum Creek volcanic complex: Miami University (Ohio) unpublished Ph.D. dissertation, 547 p.

Westgate, J.A., Preece, S.J., Froese, D.G., Pearce, N.J.G., Roberts, R.G., Demuro, M., Hart, W.K., and Perkins, W., 2008, Changing ideas on the identity and stratigraphic significance of the Sheep Creek tephra beds in Alaska and the Yukon Territory, northwestern North America: Quaternary International, v. 178, n. 1, p. 183-209, doi: 10.1016/j.quaint.2007.03.009.
http://dx.doi.org/10.1016/j.quaint.2007.03.009