Frómeta, R. A. R., J. L. Sánchez, and J. M. R. García. “Evaluation of Coffee Pulp As Substrate for Polygalacturonase Production in Solid State Fermentation”. Emirates Journal of Food and Agriculture, vol. 32, no. 2, Mar. 2020, pp. 117-24, doi:10.9755/ejfa.2020.v32.i2.2068.