1. Beck, A. (1965). J. clin. Path., 18, 307.
2. Bojalil, L. F., and Cerb6n, J. (1961). J. Bact., 81, 338. -, Cerb6n, J., and Trujillo, A. (1962). J. gen. Microbiol., 28, 333.
3. Collins, C. H. (1962). Tubercle (Edinb.), 43, 292.
4. Collins, C. H., and Massey, M. L. (1963). In Progress in Medical Laboratory. Technique. edited by F. J. Baker, vol. 2, p. 82. Butterworth, London.
5. Dross, I. C., Abbatiello, A. A. Jenney, F. S. and Cohen, A. C. (1964). Amer. Rev. resp. Dis., 89, 923.