6-9 months: Your baby's development. Zero to Three: National Center for Infants, Toddler and Families. https://www.zerotothree.org/resources/82-6-9-months-your-baby-s-development. Accessed May 25, 2017.
Teething. American Dental Association. http://www.mouthhealthy.org/en/az-topics/t/teething. Accessed May 25, 2017.
Healthy habits. American Dental Association. http://www.mouthhealthy.org/en/babies-and-kids/healthy-habits. Accessed May 30, 2017.
Shelov SP, et al. Age eight months through twelve months. In: Caring for Your Baby and Young Child: Birth to Age 5. 6th ed. New York, N.Y.: Bantam Books; 2014.