References
- Fridericia (1916) Ugeskrift for Læger, 43, p. 1899. Copenhagen
- Goodall, Strickland (1920) Practitioner, London., p. 37.
- Brachmann (1921) Lancet, p. 347.
- Romberg (1921) Lehrbuch d. Krankheiten d. Hcrzens etc., pp. 94-446. Stuttgart
- FrFischer, J. Acta radiolog, p. 179.