KÖLLER, Karlheinz. Trends bei Saat und Mineraldüngung. agricultural engineering.eu, [S. l.], v. 56, n. 6, p. 376–377, 2001. DOI: 10.15150/lt.2001.1806. Disponível em: http://195.37.233.11/landtechnik/article/view/2001-56-6-376-377. Acesso em: 5 mai. 2024.