Roberts, M. L. (1999). Direct marketing management (2nd ed.). Prentice-Hall of India.
Dyfyniad Arddull ChicagoRoberts, Mary Lou. Direct Marketing Management. 2nd ed. London: Prentice-Hall of India, 1999.
Dyfyniad MLARoberts, Mary Lou. Direct Marketing Management. 2nd ed. Prentice-Hall of India, 1999.
Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.