@article{10_1007_s10492_014_0062_6,
     author = {Andreev, Andrey and Racheva, Milena},
     title = {Two-sided bounds of eigenvalues of second- and fourth-order elliptic operators},
     journal = {Applications of Mathematics},
     pages = {371--390},
     publisher = {mathdoc},
     volume = {59},
     number = {4},
     year = {2014},
     doi = {10.1007/s10492-014-0062-6},
     mrnumber = {3233550},
     zbl = {06362234},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.1007/s10492-014-0062-6/}
}