N Engl J Med. 1976 May 20;294(21):1186-7.
The New England journal of medicine
P E Sartwell, P D Stolley
PMID: 1264128
[No abstract available.]
Keywords: Comparative Studies; Contraception; Contraceptive Methods--side effects; Diseases; Family Planning; Gallbladder Diseases; Oral Contraceptives--side effects; Research Methodology; Studies