Healthline. https://www.healthline.com/health/beauty-skin-care/order-of-skin-care#overview
Diakses pada 1 Februari 2020Health Harvard Publishing. https://www.health.harvard.edu/blog/skin-serum-what-it-can-and-cant-do-201806121402
Diakses pada 1 Februari 2020Web Md. https://www.webmd.com/beauty/features/beauty-smarts-serums-jan13#1
Diakses pada 1 Februari 2020Health. https://www.health.com/beauty/what-is-an-essence
Diakses pada 1 Februari 2020Mind Body Green. https://www.mindbodygreen.com/articles/how-to-layer-your-skincare
Diakses pada 1 Februari 2020Womenshealth Mag. https://www.womenshealthmag.com/beauty/a19952473/how-to-use-facial-toner/
Diakses pada 1 Februari 2020Harvard Health Publishing. https://www.health.harvard.edu/blog/skin-serum-what-it-can-and-cant-do-2018061214029
Diakses pada 9 Juni 2020