Elwan، S. H.، Khodair، A. A.، و Helemish، F. (1981). The effect of sodium ion uptake by Azotobacter Chroococ Cum on the Process of nitrogen fixation, nature of amino acids in cell Conjugated Protein and ammonia in Culture. مجلة كلية التربية، ع7 ، 107 - 120. مسترجع من http://search.mandumah.com/Record/655256
Elwan، S. H.، A. A. Khodair، و F. Helemish. "The Effect of Sodium Ion Uptake By Azotobacter Chroococ Cum On the Process of Nitrogen Fixation, Nature of Amino Acids in Cell Conjugated Protein and Ammonia in Culture." مجلة كلية التربية ع7 (1981): 107 - 120. مسترجع من http://search.mandumah.com/Record/655256