APA (7th ed.) Citation

Blumenthal, L. M., & Menger, K. (1970). Studies in geometry. Freeman.

Chicago Style (17th ed.) Citation

Blumenthal, Leonard M., and Karl Menger. Studies in Geometry. San Francisco, Calif: Freeman, 1970.

MLA (9th ed.) Citation

Blumenthal, Leonard M., and Karl Menger. Studies in Geometry. Freeman, 1970.