Mayo Clinic. https://www.mayoclinic.org/healthy-lifestyle/womens-health/in-depth/menstrual-cycle/art-20047186
Diakses pada 9 Mei 2019Planned Parenthood. https://www.plannedparenthood.org/learn/health-and-wellness/menstruation/how-do-i-know-if-my-menstrual-cycle-normal
Diakses pada 9 Mei 2019WebMD. https://www.webmd.com/women/normal-period
Diakses pada 9 Mei 2019