NISKANEN, R. Extractable aluminium, iron and manganese in mineral soils: II Extractability by oxalate and pyrophosphate. Agricultural and Food Science, [S. l.], v. 61, n. 2, p. 79–87, 1989. DOI: 10.23986/afsci.72356. Disponível em: https://journal.fi/afs/article/view/72356. Acesso em: 24 dec. 2024.