	Authors	Year	Title
	Plummer & Scott	1937	Upper Paleozoic ammonites in Texas. The geology of Texas, vol.3 pt.1, Bull. Texas. Univ., 3701: 1-516, fig.1-88, pl.1-41; Austin, Texas.
	Schmidt	1929	Tierische Leitfossilien des Karbon. Gürich,G.: Leitfossilien, 6. Lief.: 1-107, pl.1-23; Berlin (Borntraeger).