Strutton DR, Farkouh RA, Earnshaw SR, Hwang S, Theidel U, Kontodimas S, Klok R, Papanicolaou S. Cost-effectiveness of 13-valent pneumococcal conjugate vaccine: Germany, Greece, and The Netherlands. J Infect. 2012 Jan 1;64(1):54-67.
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