1. Barker, H. A. and Broyer, T. C., Soil Sci.53, 467?477 (1942).
2. Barnum, C. C., Phytopathology14, 238?243 (1924).
3. Bowen, G. D. and Rovira, A. D., Plant and Soil15, 263?267 (1961).
4. Curtis, R. W., Plant Physiol.32, 56?59 (1957).
5. Dwivedi, R. S., Soil Fungi of The Grasslands of Varanasi. Doctoral Thesis, Banaras Hindu University, India (1959).