Somboontanakit, C., A. Kongganun, and K. Tantiwong. “The Study of Serum Testosterone Level and Aging Male Symptoms in Thai Aging Male With Erectile Dysfunction”. Insight Urology, vol. 28, no. 2, Dec. 2007, pp. 118-24, https://he02.tci-thaijo.org/index.php/TJU/article/view/253217.