Comparative study of analgesic effect of intrathecal nalbuphine and tramadol in patients undergoing vaginal hysterectomy. International Journal of Biomedical and Advance Research, [S. l.], v. 9, n. 4, p. 136–141, 2018. DOI: 10.7439/ijbar.v9i4.4697. Disponível em: https://ssjournals.co.in/index.php/ijbar/article/view/4697. Acesso em: 12 mar. 2026.