Northrop, J. H., Kunitz, M., & Herriot, R. M. (1948). Crystalline enzymes (2nd ed., rev. and enl.). Columbia University Press.

Northrop, John Howard, Moses Kunitz, and Roger Moss Herriot. Crystalline Enzymes. 2nd ed., rev. and enl. New York: Columbia University Press, 1948.

Northrop, John Howard, et al. Crystalline Enzymes. 2nd ed., rev. and enl. Columbia University Press, 1948.