Background concentrations and quality reference values for some potentially toxic elements in soils of São Paulo State, Brazil - Nogueira, Thiago Assis Rodrigues; Abreu Junior, Cassio Hamilton; Alleoni, Luís Reynaldo Ferracciú; He, Zhenli; Soares, Marcio Roberto; Vieira, Camila dos Santos; Lessa, Luís Gustavo Frediani; Capra, Gian Franco (Journal of Environmental Management, 2018)