Adamovičs, A. and Klāsens, V. 2006. Symbiotically Fixed Nitrogen in the Soils of Latvia: Possibilities and Problems. ENVIRONMENT. TECHNOLOGIES. RESOURCES. Proceedings of the International Scientific and Practical Conference. 1, (Jun. 2006), 13–17. DOI:https://doi.org/10.17770/etr2003vol1.1972.