Roberts, M. L. (1999). Direct marketing management (2nd ed.). Prentice-Hall of India.
Chicago ZitierstilRoberts, Mary Lou. Direct Marketing Management. 2nd ed. London: Prentice-Hall of India, 1999.
MLA ZitierstilRoberts, Mary Lou. Direct Marketing Management. 2nd ed. Prentice-Hall of India, 1999.
Achtung: Diese Zitate sind unter Umständen nicht zu 100% korrekt.