HALICKI, W.; SZYMAŃCZYK, A. Nutrient Substances in Surface Water of Extensive Agriculture Areas. ENVIRONMENT. TECHNOLOGY. RESOURCES. Proceedings of the International Scientific and Practical Conference, Rezekne, Latvia, v. 1, p. 102–107, 2006. DOI: 10.17770/etr2003vol1.1993. Disponível em: https://journals23.rta.lv/index.php/ETR/article/view/1993.. Acesso em: 28 apr. 2025.