Authors Year Title
Jin, Henderson & Wardlaw 2003 Proposal for the Global Stratotype Section and Point (GSSP) for the Wuchiapingian-Changhsingian Stage boundary (Upper Permian Lopingian Series).
Permophiles 43: 8-23, 9 fig.
Wardlaw, Furnish & Nestell 1979 Geology and paleontology of the Permian beds near Las Delicias, Coahuila, Mexico.
Geological Society of America Bulletin 90 (1): 11-116, 3 figs., 2 tabls.
Wardlaw, Rudine & Nestell 2000 Conodont Biostratigraphy of the Permian Beds at Las Delicias, Coahuila, Mexico.
In: Wardlaw,B.R., Grant,R.E. & Rohr,D.M.: The Guadalupian Symposium, Smithsonian Contributions to the Earth Sciences, 32, 381-392, 10 fig., 1 pl., Washington.