Dhandio, D.J., Sulistianingsih, E. and Satyahadewi, N. 2025. INTEGRATION OF DAVIES-BOULDIN INDEX VALIDATION AND MEAN-VARIANCE EFFICIENT PORTFOLIO IN K-MEANS++ CLUSTERING FOR OPTIMIZATION OF THE LQ45 STOCK PORTFOLIO. BAREKENG: Jurnal Ilmu Matematika dan Terapan. 19, 4 (Sep. 2025), 2609-2620. DOI:https://doi.org/10.30598/barekengvol19iss4pp2609-2620.