1. Fisher, R.A.: Statistical Methods for Research Workers, ed. 10, Edinburgh, 1936, Oliver and Boyd, Ltd., chap. VII, p. 214.
2. HEREDITY AS AN AETIOLOGICAL FACTOR IN MALOCCLUSION
3. Lundstrom, A.: Tooth Size and Occlusion in Twins, ed. 2, Stockholm, 1948, A/B Fahlcrantz' Boktryckeri , chap. VII, p. 99.