Cita APA (7a ed.)

Gilleland, K., & Coel, M. (1991). 450 best sales letters for every selling situation. Prentice Hall.

Cita Chicago Style (17a ed.)

Gilleland, Karen, y Margaret Coel. 450 Best Sales Letters for Every Selling Situation. Englewood Cliffs, N.J: Prentice Hall, 1991.

Cita MLA (9a ed.)

Gilleland, Karen, y Margaret Coel. 450 Best Sales Letters for Every Selling Situation. Prentice Hall, 1991.