1. Abi-Ghanem R, Carpenter-Boggs L, Smith JL: Cultivar effects on nitrogen fixation in peas and lentils. Biol Fertil Soils 2011, 47: 115-120. 10.1007/s00374-010-0492-6
2. Amare B: Progress and future prospect in soybean research in Ethiopia. In: Proc 19th National crop improvement Conefrence. Institute of agricultural Research, Addis Ababa, Ethiopia; 1987:252-265.
3. Asfaw A, Tesfaye A, Alamire S, Atnafe M: Soybean genetic improvement in Ethiopia. In Food and Forage Legumes of Ethiopia: Progress and Prospects. Proceedings of the Workshop on Food and Forage Legumes 22–26 September 2003. Edited by: Kemal A, Seid A, Surendra B, Gemechu K, Malhotra RS, Makkouk K, Halila MH. Addis Ababa, Ethiopia: International Center for Agricultural Research in the Dry Areas (ICARDA); 2006:95-102.
4. Balatti PA, Pueppke SG: Identification of North American soybean lines that form nitrogen-fixing nodules with Rhizobium fredii USDA257. Can J Plant Sci 1992, 72: 49-55. 10.4141/cjps92-006
5. Bello AB, Ceron-Dias WA, Nickell CD, Elsheriff EO, Davis LC: Influence of cultivar, between-row spacing and plant population of fixation of soybeans. Crop Sci 1980, 20: 751-775. 10.2135/cropsci1980.0011183X002000060018x