Nickels, W. G., McHugh, J. M., & McHugh, S. M. (2005). Concept mastery toolkit CD-ROM to accompany Understanding business (séptima edición.). McGraw-Hill.

Nickels, William G., James M. McHugh, and Susan M. McHugh. Concept Mastery Toolkit CD-ROM to Accompany Understanding Business. séptima edición. Boston, MA: McGraw-Hill, 2005.

Nickels, William G., et al. Concept Mastery Toolkit CD-ROM to Accompany Understanding Business. séptima edición. McGraw-Hill, 2005.