de Carvalho, V.D. et al. (1994) “Relationship between the physical-chemical and chemical composition of green coffee and the quality of coffee beverage I - Polyphenoloxidase and peroxidase activity, color index and titratable acidity”, Pesquisa Agropecuaria Brasileira, 29(3), pp. 449–454. doi:10.1590/S1678-3921.pab1994.v29.4074.