Elkordy, A. M., and I. A. Schanzer. “Fruit Morphology in Galium Section Platygalium (Rubiaceae) and Its Potential Taxonomic Significance”. Turczaninowia, Vol. 18, no. 1, 1, pp. 82–89, doi:10.14258/turczaninowia.18.1.9.