1. V. B. Veinberg and D. K. Sattarov, Optics of Light Conductors [in Russian], Leningrad (1963).
2. P. I. Branemark, Scand. J. Clin. Lab. Invest.,11, Suppl. 38, (1959).
3. W. H. Gaskell, J. Anat. (Paris),11, 720 (1877).
4. H. Heileman, Arch. Anat. Physiol., 45 (1902).
5. M. H. Knisely, Anat. Rec.,58, 73 (1934).