H. Dyer,
The Fish in Room 11. Scholastic Paperbacks, 2005, p. 160.
J. Dusheck,
Asking About Life. Houghton Mifflin Harcourt (HMH), 1997.
P. M. Dunne, Lusch, R. F., and Griffith, D. A.,
Retailing. Thomson South-Western, 2001, p. 594.
M. Dugopolski,
College Algebra (2nd Edition). Addison Wesley Publishing Company, 1998.
A. J. DuBrin, Geerinck, T. M., Mintz, S., McMurry, L. O., and Jones, J. H.,
HUMAN RELATN:INTRPSNLJOB ORIENTD SK. Prentice Hall Canada, 2001.