Coulter, S.E., Pilcher, J.R., Plunkett, Gill, Baillie, Mike, Hall, V.A., Steffensen, J.P., Vinther, B.M., Clausen, H.B., and Johnsen, S.J., 2012, Holocene tephras highlight complexity of volcanic signals in Greenland ice cores: Journal of Geophysical Research, v. 117, 11 p., doi:10.1029/2012JD017698, 2012