1. Avery, E. E., Morch, E. T., and Benson, D. W. (1956). J. thorac. Surg., 32, 291.
2. Bjork, V. 0. (1960). Ibid., 39, 179.
3. Bjork, V. 0. and Engstrom, C. G. (1955). Ibid., 30, 356.
4. Bjork, V. 0. (1957). Ibid., 34, 228.
5. Buckley, J. J., Van Bergen, F. H., and Thiel, N. A. (1960). Anesth. P Analg. Curr. Res., 39, 121.