Sumber:

• https://www.expatwoman.com/ewmums/en/babies/feeding/8-types-nipples-and-their-impact-breastfeeding?
• https://www.verywellfamily.com/breastfeeding-with-different-nipple-shapes-and-sizes-431669
• https://youaremom.com/health/types-of-nipples-influence-on-breastfeeding/