Cita APA

Willman, H. B., Swann, D. H., & Frye, J. C. (1958). Stratigraphic policy of the Illinois State geological survey. Division of the Illinois State geological survey.

Citación estilo Chicago

Willman, Harold B., David H. Swann, and John C. Frye. Stratigraphic Policy of the Illinois State Geological Survey. Urbana: Division of the Illinois State geological survey, 1958.

Cita MLA

Willman, Harold B., David H. Swann, and John C. Frye. Stratigraphic Policy of the Illinois State Geological Survey. Urbana: Division of the Illinois State geological survey, 1958.