@article{CMUC_1971__12_3_a2,
     author = {Najzar, Karel},
     title = {Error-estimates for the {Ritz's} method of finding eigenvalues and eigenfunctions},
     journal = {Commentationes Mathematicae Universitatis Carolinae},
     pages = {485--501},
     publisher = {mathdoc},
     volume = {12},
     number = {3},
     year = {1971},
     mrnumber = {0301921},
     zbl = {0246.49037},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/CMUC_1971__12_3_a2/}
}