Penentuan nilai SPF emulsi gel tabir surya yang mengandung etil para metoksisinamat hasil isolasi dari rimpang kencur kaempferia galanga l = determination of SPF value of sunscreen emulsion gel containing ethyl para methoxycinnamate a chemical constituent derived from kaempferia galanga l / Henny Puspita Siagian (Fakultas Farmasi Universitas Indonesia, 2014)