Trinovita, Elsa, Valencia, Regina, Shinta, Herlina, Toemon, Angeline, AND Ysrafil, Ysrafil. " Evaluation of combination patch of vetel leaf extract (Piper sp.) - ultrasonic assisted extraction (UAE) as a transdermal delivery system on fibroblast cell formation and collagen density" JURNAL ILMU KEFARMASIAN INDONESIA [Online], Volume 23 Number 1 (30 April 2025)