L.-L. Güiza-Castillo, E.-H. Pinzón-Sandoval, P.-A. Serrano-Cely, G.-E. Cely-Reyes, and P.-C. Serrano-Agudelo, “Estimation and correlation of chlorophyll and nitrogen contents in Psidium guajava L. with destructive and non-destructive methods”, Rev. Colomb. Cienc. Hortic, vol. 14, no. 1, pp. 26–31, Jan. 2020.