1. 1) O. Fejerskov and B. H. Clarkson: Fluoride in Dentistry, ed. by O. Fejerskov, J. Ekstrand and B. A. Burt, (Munksgaard, Copenhagen, 1996) pp. 187–213.
2. 2) G. Rolla and J. Ekstrand: Fluoride in Dentistry, ed. by O. Fejerskov, J. Ekstrand and B. A. Burt, (Munksgaard, Copenhagen, 1996) pp. 215–229.
3. 3) R. Hamilton and G. H. W. Bowden: Fluoride in Dentistry, ed. by O. Fejerskov, J. Ekstrand and B. A. Burt, (Munksgaard, Copenhagen, 1996) pp. 230–251.
4. 4) J. M. ten Cate and J. D. M. Featherstone: Fluoride in Dentistry, ed. by O. Fejerskov, J. Ekstrand and B. A. Burt, (Munksgaard, Copenhagen, 1996) pp. 252–272.
5. 5) H. S. S. Siirila and M. Kononen: Int. J. Oral Maxillofac. Implants 6 (1991) 50–54.