F. Y. BATUBARA, “DIFFERENCES IN THE EFFECT OF APPLYING 6% AND 12% HYDROXYAPATITE PASTE FROM DUCK EGGSHELLS (ANAS PLATYRHYNCHOS) WITH CASEIN PHOSPHOPEPTIDE-AMORPHOUS CALCIUM PHOSPHATE (CPP-ACP) AS REMINERALIZING MATERIALS ON ENAMEL SURFACE HARDNESS (IN VITRO)”, Int J App Pharm, vol. 17, no. 6, pp. 478–484, Nov. 2025.