Thorson, T.B. & Watson, D.E. & Cowan, C.M. (1976)
The status of the Lake Nicaragua shark: an updated appraisal. In Investigation of the ichthyofauna of Nicaraguan lakes, edited by T.B. Thorson. Lincoln, Nebraska, University of Nebraska Press: 561–574

Cowan, C.M. (1976)
Serum Protein Variation in the Bull Shark, Carcharhinus leucas Müller and Henle, 1841. In Investigation of the ichthyofauna of Nicaraguan lakes, edited by T.B. Thorson. Lincoln, Nebraska, University of Nebraska Press: 585–590

Thorson, T.B. & Cowan, C.M. & Watson, D.E. (1976)
Body Fluid Solutes of Juveniles and Adults of the Euryhaline Bull Shark Carcharhinus leucas from Freshwater and Saline Environments. In Investigation of the ichthyofauna of Nicaraguan lakes, edited by T.B. Thorson. Lincoln, Nebraska, University of Nebraska Press: 599–612

Thorson, T.B. & Watson, D.E. & Cowan, C.M. (1976)
The Status of the Freshwater Shark of Lake Nicaragua. In Investigation of the ichthyofauna of Nicaraguan lakes, edited by T.B. Thorson. Lincoln, Nebraska, University of Nebraska Press: 385–402

Thorson, T.B. & Cowan, C.M. & Watson, D.E. (1973)
Body fluid solutes of juveniles and adults of the euryhaline bull shark Carcharhinus leucas from freshwater and saline environments. Physiological Zoology, 46(1), 29–42

Cowan, C.M. (1971)
Serum protein variation in the bull shark, Carcharhinus leucas muller and henle, 1841. International Journal of Biochemistry, 2(12), 691–696
DOI: 10.1016/0020-711X(71)90061-9

Thorson, T.B. & Cowan, C.M. & Watson, D.E. (1967)
Potamotrygon spp.: elasmobranchs with low urea content. Science, 158, 375–377

Thorson, T.B. & Watson, D.E. & Cowan, C.M. (1966)
The status of the freshwater shark of Lake Nicaragua. Copeia, 1966(3), 385–402

Thorson, T.B. & Cowan, C.M. & Watson, D.E. (1966)
Sharks and sawfish in the Lake Izabal-Rio Dulce system, Guatemala. Copeia, 1966(3), 620–622