Dewey, M., Comaromi, J. P., Beall, J., Matthews, W. E., & New, G. R. (1989). Dewey decimal classification and relative index (20th ed.). Albany, N.Y: Forest Press.

Dewey, Melvil, John P. Comaromi, Julianne Beall, Winton E. Matthews, and Gregory R. New. Dewey Decimal Classification and Relative Index. 20th ed. Albany, N.Y: Forest Press, 1989.

Dewey, Melvil, et al. Dewey Decimal Classification and Relative Index. 20th ed. Albany, N.Y: Forest Press, 1989.