	Authors	Year	Title
	Gordon	1965	Carboniferous Cephalopods of Arkansas. Professional Papers, U.S. Geological Survey, 460: 1-322, fig.1-96, pl.1-32; Washington. [imprint 1964].
	Gordon	1969	An Early Reticuloceras Zone Fauna From the Hale Formation in Northwestern Arkansas. Geological Survey Professional Paper 613-A: A1-A21, 12 text-fig., 2 pl. Washington. [imprint 1968].