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Diakses pada 05 April 2019NHS. https://www.nhs.uk/conditions/periods/delayed-periods/
Diakses pada 05 April 2019WebMD. https://www.webmd.com/women/why-is-my-period-so-random#1
https://www.webmd.com/women/normal-period
Diakses pada 05 April 2019