Drupal-Bibcite31<style face="normal" font="default" size="100%">Drospirenone- and levonorgestrel-containing oral contraceptives and the risk of gallbladder disease</style><style face="normal" font="default" size="100%">Drospirenone- and levonorgestrel-containing oral contraceptives and the risk of gallbladder disease</style>