Pennsylvanian invertebrates of the Mazon Creek area, Illinois: the morphology and affinities of Tullimonstrum

by Johnson, Ralph Gordon, 1927-1976
Published 1969

New fossil polychaete from Essex, Illinois /

by Thompson, Ida, Johnson, Ralph Gordon, 1927-1976
Published 1977

The nature of shield abnormalities in the turtle shell /

by Zangerl, Rainer, 1912-2004, Johnson, Ralph Gordon, 1927-1976
Published 1957

Pennsylvanian invertebrates of the Mazon Creek, area, Illinois: the Essex fauna and medusae

by Johnson, Ralph Gordon, 1927-1976, Richardson, Eugene S (Eugene Stanley), Jr., 1916-1983
Published 1968