1. A. A. Voitkevich, and L. N. Kuleshova, Byull. éksper. biol. 6 (1962), p. 84
2. L. D. Liozner (Ed.), Regeneration of Organs in Mammals [in Russian], Moscow (1960), p. 253.
3. G. V. Segida, Byull. éksper. biol., 11 (1962), p. 88.
4. B. Fischer, Arch. mikr. Anat., 77 (1911), p. 1.