Nisardi, Muhammad Rifki, et al. “Optimization of Stock Portfolio Investment Based on K-Means Clustering Using Markowitz Method (A Case Study: IDX-MES BUMN17 Index)”. Jurnal Matematika, Statistika Dan Komputasi, vol. 22, no. 1, Sept. 2025, pp. 187-98, doi:10.20956/j.v22i1.43875.