Immunostimulating Study of Active Agent Fraction from Sungkai (Peronema canescens Jack.) Leaf from SARS-COV-2 Virus Antigen Exposure to NK and CD8+T Cells, Dillasamola, Dwisari, Wahyuni Fatma Sri, Rita Rauza Sukma,, Alen Yohanes, Umar Salman, and Aldi Yufri , Pharmacognosy Journal, August 2022, Volume 14, Issue 4, p.344-351, (2022)