1. Achauer, C. W. (1969): Origin of Capitan Formation, Guadalupe Mountains, New Mexico and Texas.—Bulletin of the American Association of Petroleum Geologists,53, 2314–2325, Boulder
2. Babcock, J. A. (1977): Calcareous algae, organic boundstones, and the genesis of the upper Capitan Limestones (Permian, Guadalupian), Guadalupe Mountains, west Texas and New Mexico.—In:Hileman, M. E. & Mazzullo, S. J. (eds.): Upper Guadalupian facies, Permian reef complex, Guadalupe Mountains, New Mexico and west Texas.—Society of Economic Paleontologists and Mineralogists, Permian Basin Section, Special Publication77/6, 3–44, Tulsa
3. — (1979): Calcareous algae and algal Problematica of the Capitan reef (Permian), Guadalupe Mountains, west Texas and New Mexico, U.S.A.—Bulletin Centre de Recherche Exploration-Production Elf-Aquitaine,3, 419–428, Pau
4. — (1986): The puzzle of alga-like Problematica, or rummaging around in the algal wastebasket.—In:Hoffman, A. &Nitecki, M. H. (eds.), Problematic fossil taxa. 12–26, Oxford University Press, New York.
5. Babcock, J. A., Pray, L. & Yurewicz, D. (1977): Locality guide I, Stop I, Upper Capitan-Massive, mouth of Walnut Canyon.—In:Pray, L. C. & Esterban, M. (eds.): Road logs and locality guides, v. 2., Upper Guadalupian facies, Permian reef complex, Guadalupe Mountains, New Mexico and west Texas.—Society of Economic Paleontologists and Mineralogists, Permian Basin Section, Special Publication77/16, G-17-G,-40, Tulsa