APA
Lamm S., Couzens G. S., . (2005). The hardness factor : how to achieve your best health and sexual fitness at any age. New York: HarperCollins.
Chicago
Lamm Steven, Couzens Gerald Secor, . 2005. The hardness factor : how to achieve your best health and sexual fitness at any age. New York: HarperCollins.
Harvard
Lamm S., Couzens G. S., . (2005). The hardness factor : how to achieve your best health and sexual fitness at any age. New York: HarperCollins.
MLA
Lamm Steven, Couzens Gerald Secor, . The hardness factor : how to achieve your best health and sexual fitness at any age. New York: HarperCollins. 2005.