@article{10_1090_S0894_0347_98_00274_4,
     author = {Peller, V.},
     title = {Factorization and approximation problems for matrix functions},
     journal = {Journal of the American Mathematical Society},
     pages = {751--770},
     publisher = {mathdoc},
     volume = {11},
     number = {4},
     year = {1998},
     doi = {10.1090/S0894-0347-98-00274-4},
     url = {http://geodesic.mathdoc.fr/articles/10.1090/S0894-0347-98-00274-4/}
}