MacLeod S, Tkatch R, Kraemer S, Fellows A, McGinn M, Schaeffer J, Yeh CS. The impact of COVID-19 on informal caregivers in the US. Int J Aging Res. 2021 Jan;4(87).
Rothman KJ, Glass RL, Espinal F, Velez H. Caries-free teeth in the absence of fluoride ion. J Public Health Dent. 1972;32(4):225-8. doi: 10.1111/j.1752-7325.1972.tb03977.x