Sanjaya, William, and Bambang B. Siswanto. “Effect of Beta Blocker Therapy on Survival in Severe Heart Failure”. Medical Journal of Indonesia 11, no. 3 (August 1, 2002): 174-5. Accessed April 24, 2024. http://mji.ui.ac.id/journal/index.php/mji/article/view/63.