J Trussell, J A Leveque, J D Koenig, R London, S Borden, J Henneberry, K D LaGuardia, F Stewart, T G Wilson, S Wysocki,
The economic value of contraception: a comparison of 15 methods. American Journal of Public Health. ,vol. 85, pp. 494- 503 ,(1995) ,
10.2105/AJPH.85.4.494