Rieckehoff, Irma G., and A. Ríos. “Occurrence of Pectin Methylesterase in Guavas”. The Journal of Agriculture of the University of Puerto Rico 40, no. 2 (April 1, 1956): 90–92. Accessed December 22, 2024. https://revistas.upr.edu/index.php/jaupr/article/view/12639.