1. O. Leppin, Deut. Med. Wochschr., 22 (28), 454, (1896).
2. L.G. Stevens, Brit. Med. J., 1:998, (1896).
3. D. Walsh, Brit. Med. J, 2:207–216, (1897).
4. H. Heineke, Munch. Med. Wochschr., 50:2090–2092, (1903).
5. J. Bergonié, and L. Tribondeau, Gompt. Rend. Soc. Biol., 57, 400–402, (1904).