1. Bhatia, R.: Matrix Analysis. Springer, New York (1997)
2. Chen, X.S., Li, W.: Relative perturbation bounds for the subunitary polar factor under unitarily invariant norms. Adv. Math. 35, 178–184 (2006). (in Chinese)
3. Elden, L.: A weighted pseudoinverse, generalized singular values and constrained least squares problmes 22, 487–502 (1982)
4. Fierro, R.D., Bunch, J.R.: Orthogonal projection and total least squares. Numer. Linear Algebra Appl. 2, 135–153 (1995)
5. Golub, G.H., Van Loan, C.F.: Matrix Computations, Johns Hopkins Studies in the Mathematical Sciences, 3rd edn. Johns Hopkins University Press, Baltimore, MD (1996)