Li, Chi-Kwong, and Stephen Pierce. “Linear Preserver Problems”. The American Mathematical Monthly, vol. 108, no. 7, 2001, p. 591, https://doi.org/10.2307/2695268.
Li, C.-K., & Pierce, S. (2001). Linear Preserver Problems. The American Mathematical Monthly, 108(7), 591. https://doi.org/10.2307/2695268
Li CK, Pierce S. Linear Preserver Problems. The American Mathematical Monthly. 2001;108(7):591.