Markowitz, Harry «Portfolio Selection». The Journal of Finance, 7, 1, 3-1952, pàg. 77. DOI: 10.2307/2975974.
Markowitz, H.M. «The Optimization of a Quadratic Function Subject to Linear Constraints». Naval Research Logistics Quarterly, 3, 1–2, 3-1956, pàg. 111–133. DOI: 10.1002/nav.3800030110.