Cole, F., Ecker, JG., & Gochet, W. (1982). A Reduced Gradient-method for Quadratic Programs With Quadratic Constraints and Lp-constrained Lp-approximation Problems. European Journal of Operational Research, 9(2), 194-203. https://doi.org/10.1016/0377-2217(82)90073-X (Original work published 1982)