1. Bertrand, D., C.R. Acad. Sci., Paris, 213, 254 (1941).
2. Mulder, E. G., “Antonie van Leeuwenhoek”, 6, 99 (1939).
3. Mulder, E. G., Plant and Soil, 1, 1, 94 (1948).
4. Nicholas, D. J. D., and Fielding, A. H., Long Ashton Ann. Rept., 126 (1947).
5. Nicholas, D. J. D., Abstracts of Proceedings of 1st International Congress of Biochemistry, Cambridge, Abstract No. 121/2, 302 (1949).