Tobita, S and Ito, O and Matsunaga, R and Rao, T P and Rego, T J and Johansen, C and Yoneyama, T (1994) Field evaluation of nitrogen fixation and use of nitrogen fertilizer by sorghum/pigeonpea intercropping on an Alfisol in the Indian semi-arid tropics. Biology and Fertility of Soils, 17 (4). pp. 241-248. ISSN 0178-2762