Goodfriend G.A, Ellis G.L.  2000.  Stable carbon isotope record of middle to late Holocene climate changes from land snail shells at HInds Cave, Texas (Book Section). Holocene Environmental Change on the Great Plains of North America. 67:47-60.

Goodfriend G.A, Ellis G.L, Toolin L.J.  1999.  Radiocarbon age anomalies in land snail shells from Texas: Ontogenetic, individual, and geographic patterns of variation. Radiocarbon. 41(2):149-156.