E, Aleksiev, Ugrinov R, and Hristov Kr. “Periodontal Ligament Stem Cells-Current Review of the Literature”. International Journal of Medical Science and Clinical Invention 6, no. 05 (May 4, 2019): 4433–4437. Accessed April 17, 2024. http://valleyinternational.net/index.php/ijmsci/article/view/2078.