Dewey, M., Beall, J., Matthews, W. E., Mitchell, J. S., & New, G. R. (1996). Dewey decimal classification and relative index (Ed. 21.). Albany, N.Y.: Forest Press, a division of OCLC Online Computer Library Center.

Dewey, Melvil, Julianne Beall, Winton E. Matthews, Joan S. Mitchell, và Gregory R. New. Dewey Decimal Classification and Relative Index. Ed. 21. Albany, N.Y.: Forest Press, a division of OCLC Online Computer Library Center, 1996.

Dewey, Melvil, et al. Dewey Decimal Classification and Relative Index. Ed. 21. Albany, N.Y.: Forest Press, a division of OCLC Online Computer Library Center, 1996.