1. Osler, W.—The Principles and Practice of Medicine. 1897, p. 204.
2. Forchheimer, F—The Pronhylaxis and Treatment of Internal Disease. 1908, p. 77.
3. Spolverini, L.—Rivista di Clinica Pediatrica. Firenze, Dic. 1919, p. 617.
4. Woodhead.—Osler, loc. cit.
5. Weisenberg, T. H.—Posey and Spiller: The Eye and Nervous System. p. 605.