_:vb50949308 "url:https://www.ncbi.nlm.nih.gov/pubmed/23939500"^^ . _:vb50949308 . _:vb50949308 . _:vb50949308 "A female reproductive system disease that is characterized by the absence of menstruation."^^ . _:vb50949308 . _:vb50949308 . _:vb50949308 .