Wintsch, R. P., Kunk, M. J., & Epstein, J. B. (1996). 40 Ar/ 39 Ar whole-rock data constraints on Acadian diagenesis and Alleghanian cleavage in the Martinsburg Formation, eastern Pennsylvania. American Journal of Science, 296(7), 766–788. https://doi.org/10.2475/ajs.296.7.766