Nachtigall, G.R., Nogueirol, R.C. and Alleoni, L.R.F. (2007) “Forms of copper in vineyard soils as affected by pH and poultry litter application”, Pesquisa Agropecuaria Brasileira, 42(3), pp. 427–434. doi:10.1590/S1678-3921.pab2007.v42.7584.