D’Alessio, Alessio, et al. “Cancer Stem Cells from Peritumoral Tissue of Glioblastoma Multiforme: The Possible Link Between Tumor Development and Progression”. Italian Journal of Anatomy and Embryology, vol. 122, no. 1, Oct. 2017, p. 70, https://oajournals.fupress.net/index.php/ijae/article/view/1831.