Dewey, M., Comaromi, J. P. (. P., Beall, J., Matthews, W. E., & New, G. R. (1989). Dewey decimal classification and relative index (Ed. 20.). Albany, N.Y.: Forest Press, a division of OCLC Online Computer Library Center.

Dewey, Melvil, John P. (John Phillip) Comaromi, Julianne. Beall, Winton E. Matthews, and Gregory R. New. Dewey Decimal Classification and Relative Index. Ed. 20. Albany, N.Y.: Forest Press, a division of OCLC Online Computer Library Center, 1989.

Dewey, Melvil, et al. Dewey Decimal Classification and Relative Index. Ed. 20. Albany, N.Y.: Forest Press, a division of OCLC Online Computer Library Center, 1989.