APA
Guffey M. E., Seefer C. M. & Guffey M. E. (2007). Mary Ellen Guffey's essentials of business communication. Mason, OH: Thomson/South-Western.
Chicago
Guffey Mary Ellen, Seefer Carolyn M and Guffey Mary Ellen. 2007. Mary Ellen Guffey's essentials of business communication. Mason, OH: Thomson/South-Western.
Harvard
Guffey M. E., Seefer C. M. and Guffey M. E. (2007). Mary Ellen Guffey's essentials of business communication. Mason, OH: Thomson/South-Western.
MLA
Guffey Mary Ellen, Seefer Carolyn M and Guffey Mary Ellen. Mary Ellen Guffey's essentials of business communication. Mason, OH: Thomson/South-Western. 2007.