@article{10_4171_dm_21,
     author = {A. B\"ottcher},
     title = {On the approximation numbers of large {Toeplitz} matrices},
     journal = {Documenta mathematica},
     pages = {1--29},
     year = {1997},
     volume = {2},
     doi = {10.4171/dm/21},
     url = {http://geodesic.mathdoc.fr/articles/10.4171/dm/21/}
}