Immunostimulating Activity of Sungkai Leaf Stigmasterol Isolate against Cluster Differentiated 8+ T (CD8+T) from Covid 19 Disease Exposure, Dillasamola, Dwisari, Wahyuni Fatma Sri, Rita Rauza Sukma, and Aldi Yufri , Pharmacognosy Journal, October 2023, Volume 15, Issue 5, p.738-742, (2023)