1. Beach, C. H. (1935). J. Amer. med. Ass., 105, 871.
2. Beaumont, G. E., and Robertson, J. D. (1939). Lancet, 1, 682.
3. Benestad, G. (1937). Nord. med. Tidskr., 14, 1741.
4. Campbell, M., and Suzman, S. S. (1934). Guy's Hosp. Reports, 84, 281.
5. Fournier, J. C. M. (1942). Proc. Mayo Clin., 17, 212.