Avalos, G., and S. S. Mulkey. “Photochemical Efficiency of Adult and Young Leaves of the Neotropical Understory Shrub <i>Psychotria limonensis</i≫ (Rubiaceae) in Response to Changes in the Light Environment”. Revista De Biología Tropical, vol. 52, no. 4, Dec. 2004, pp. 839–844, https://revistas.ucr.ac.cr/index.php/rbt/article/view/15498.