Brown DS, Johnson FR, Poulos C, Messonnier ML. Mothers' preferences and willingness to pay for vaccinating daughters against human papillomavirus. Vaccine. 2010 Feb 1;28(7):1702-8.
Jick H, Hannan MT, Stergachis A, Heidrich F, Perera DR, Rothman KJ. Vaginal spermicides and gonorrhea. JAMA. 1982 Jan 1;248(13):1619-21.