@ARTICLE {RAO:1977b, title = {Nitrogenase activity of Rhizobium sp. strain 1552 on defined medium}, author = {Rao, R. V. }, journal = {Plant Science Letters}, year = {1977}, volume = {8}, number = {4}, pages = {363--366}, issn = {0304-4211}, url = {http://www.sciencedirect.com/science/article/pii/0304421177901559}, doi = {10.1016/0304-4211(77)90155-9}, }