Gaya APA

Sachs, W, S., Katzenstein, H. (1992). Direct marketing / Herbert Katzenstein, William S. Sachs (Cet.7). New York: Macmillan Publishing.

Gaya MLA

Sachs, William, S.., Katzenstein, Herbert. "Direct marketing / Herbert Katzenstein, William S. Sachs". Cet.7 New York: Macmillan Publishing, 1992. Textbook.