Nugroho, M., & Nurcahyo, Y. E. (2019). Investment Decision Making: The System Performance of the Portfolio of Shares on Index Business 27 (2017-2018) using the Model of Constant Correlation. International Review of Management and Marketing, 9(5), 95–103. Retrieved from https://www.econjournals.com/index.php/irmm/article/view/8091