APA (7th ed.) Citation

ScienceDirect (Online service), Kaplan, N. O., & Colowick, S. P. (1955). Preparation and assay of enzymes. Academic Press.

Chicago Style (17th ed.) Citation

ScienceDirect (Online service), Nathan O. Kaplan, and Sidney P. Colowick. Preparation and Assay of Enzymes. London: Academic Press, 1955.

MLA (9th ed.) Citation

ScienceDirect (Online service), et al. Preparation and Assay of Enzymes. Academic Press, 1955.