APA

Beckwith H., . (1997). Selling the invisible. New York: Warner Books.

Chicago

Beckwith Harry, . 1997. Selling the invisible. New York: Warner Books.

Harvard

Beckwith H., . (1997). Selling the invisible. New York: Warner Books.

MLA

Beckwith Harry, . Selling the invisible. New York: Warner Books. 1997.