Morais, Heverly, et al. “Microclimatic Characterization and Productivity of Coffee Plants Grown under Shade of Pigeon Pea in Southern Brazil”. Pesquisa Agropecuaria Brasileira, vol. 41, no. 5, May 2006, pp. 763-70, doi:10.1590/S1678-3921.pab2006.v41.7204.