@article{RM_1996_51_3_a3,
     author = {Yu. V. Egorov and V. A. Kondrat'ev},
     title = {Estimates for the first eigenvalue in some {Sturm--Liouville} problems},
     journal = {Trudy Matematicheskogo Instituta imeni V.A. Steklova},
     pages = {439--508},
     publisher = {mathdoc},
     volume = {51},
     number = {3},
     year = {1996},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/RM_1996_51_3_a3/}
}