Refi Tri Anika, Nabila Febriyana, Siti Maisyaroh, and Maria Yovita R Pandin, “Analysis of the Effect of Stock Portfolio Diversification with the Markowitz Method Approach to Portfolio Risk and Return on Idxbumn20 Index Stocks”, Ijemr, vol. 3, no. 1, pp. 26–40, Apr. 2024.