Gonçalves, P. de S., Cardoso, M. and Sáes, L. A. (1991) “Performance of four rubber tree clones at the Ribeira river valley, state of São Paulo, Brazil”, Pesquisa Agropecuaria Brasileira, 26(5), pp. 681–690. doi: 10.1590/S1678-3921.pab1991.v26.3392.