1. Wilson, J. L.: International Clinics, Vol. I, Series 47, March, ‘37.
2. Coryllos and Birnbaum: Archives Surgery, Vol. I, P. 501.
3. Lee and Tucker: Annals of Surgery, 138, 6.
4. Parodi, F.: “La Mecanique Pulmonaire” Masson et Cie, Paris, ‘33.
5. Wilson, J. L.: International Clinics, Vol. I, Series 47, March, ‘37. quoting Fraentzel, Orth, Schiminke, and Kjaergaard.