DHANDIO, D. J.; SULISTIANINGSIH, E.; SATYAHADEWI, N. 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, v. 19, n. 4, p. 2609-2620, 1 set. 2025.