OPERACZ, Maciej; KENTZER, Andrzej; NOWACZYK, Łukasz. The content of nitrogen compounds in the Wel river in the light of the Nitrates Directive. Ecological Questions, [S. l.], v. 15, n. 1, p. 23–29, 2013. DOI: 10.12775/v10090-011-0031-6. Disponível em: https://apcz.umk.pl/EQ/article/view/v10090-011-0031-6. Acesso em: 13 dec. 2025.