1. Lilienfeld, A. M. Epidemiology of Mongolism. Baltimore: Johns Hopkins Press, 1969, p. 22.
2. Epidemiology of congenital anomalies of the central nervous system with special reference to patterns in the State of Victoria, Australia;Collmann R. D.;J. Ment. Defic. Res,1962
3. A chromosome survey of the total population of mentally subnormal in north-east Scotland;Johnston A. W.;Clin. Genet,1976
4. A survey of 972 cytogenetically examined cases of Down's syndrome;Gardner R. J. M.;N.Z. Med. J,1973
5. A t(21q21q) Ring Chromosome