APA
Knapp D., . (1999). A Guide to customer service skills for the help desk professional. Thomson, Australia: .
Chicago
Knapp Donna, . 1999. A Guide to customer service skills for the help desk professional. Thomson, Australia: .
Harvard
Knapp D., . (1999). A Guide to customer service skills for the help desk professional. Thomson, Australia: .
MLA
Knapp Donna, . A Guide to customer service skills for the help desk professional. Thomson, Australia: . 1999.