	Authors	Year	Title
	Davis	1972	Mature modifications and dimorphism in selected Late Paleozoic ammonoids. Bulletins of American Paleontology, 62 (272): 27-130, pls.3-21, Ithaca, NY.
	Davis, Landman & Dommergues	1996	Mature Modifications and Dimorphism in Ammonoid Cephalopods. [Davis,R.A., Landman, N.H., Dommergues, D.M., Marchand, D. & Bucher, H.] In: Ammonoid Paleobiology, N.H.Landman, K.Tanabe & R.A.Davis [eds.], 463-539, 15 figs, 1 tabl., New York (Plenum).
	Girty	1908	The Guadalupian Fauna. Professional Papers, U.S. Geological Survey, 58: 1-651, pl.1-31; Washington.
	Miller & Furnish	1940c	Permian ammonoids of the Guadalupe Mountain Region and adjacent areas. Special Papers of the Geological Society of America, 26: 1-242, fig.1-59, pl.1-44; Baltimore.
	Sheng	1988	Early Lower Permian ammonoids of the Urulung Formation from Luobadui, Xizang (Tibet). Tectonic evolution of the lithosphere of the Himalayas: 123-148, fig.1-11, pl.1-3; Beijing.