APA (7th ed.) Citation

Nunn, G. E. (1977). The geographical conceptions of Columbus: A critical consideration of four problems. Octagon Books.

Chicago Style (17th ed.) Citation

Nunn, George E. The Geographical Conceptions of Columbus: A Critical Consideration of Four Problems. New York: Octagon Books, 1977.

MLA (9th ed.) Citation

Nunn, George E. The Geographical Conceptions of Columbus: A Critical Consideration of Four Problems. Octagon Books, 1977.