Asmara, K., M. Marisha, H. Hengky, F. Agustanti, and H. P. Tampubolon. “Erectile Dysfunction and Health-Related Quality of Life in Elderly Males”. Universa Medicina, vol. 30, no. 3, Dec. 2011, pp. 182-8, doi:10.18051/UnivMed.2011.v30.182-188.