Lusiana, Novita, and Ika Putri Damayanti. “Risk Factors of Fertile Age in the Inability of the Use of Long Term Contraception Method in Pekanbaru”. Science Midwifery, vol. 10, no. 1, October, Dec. 2021, pp. 481-7, https://midwifery.iocspublisher.org/index.php/midwifery/article/view/251.