Guffanti, Marianne, Brantley, Steven R., Cervelli, Peter F., Nye, Christopher J., Serafino, George N., Siebert, Lee, Venezky, Dina Y., and Wald, Lisa. 2007. "Technical-Information Products for a National Volcano Early Warning System." Reston, VA: U.S. Department of the Interior;U.S. Geological Survey.