Healthline. https://www.healthline.com/nutrition/get-a-flat-stomach
Diakses pada 13 April 2020Medical News Today. https://www.medicalnewstoday.com/articles/324636
Diakses pada 13 April 2020Health. https://www.health.com/fitness/13-flat-belly-tricks
Diakses pada 13 April 2020