Gaya APA
Roberts, M, L., Berger, P, D. (1989).
Direct marketing management .
Englewood Cliffs, New Jersey:
Prentice-Hall.
Gaya MLA
Roberts, Many, Lou., Berger, Paul, D..
"Direct marketing management".
Englewood Cliffs, New Jersey:
Prentice-Hall,
1989.
Text.