@article{ZNSL_2008_359_a13,
     author = {M. N. Yakovlev},
     title = {An error bound of the {Ritz} method for a~singular second-order differential equation},
     journal = {Zapiski Nauchnykh Seminarov POMI},
     pages = {208--215},
     publisher = {mathdoc},
     volume = {359},
     year = {2008},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/ZNSL_2008_359_a13/}
}