@article{10_4153_CMB_1971_005_9,
     author = {Faierman, M.},
     title = {On a {Perturbation} in a {Two-Parameter} {Ordinary} {Differential} {Equation} of the {Second} {Order}},
     journal = {Canadian mathematical bulletin},
     pages = {25--33},
     year = {1971},
     volume = {14},
     number = {1},
     doi = {10.4153/CMB-1971-005-9},
     url = {http://geodesic.mathdoc.fr/articles/10.4153/CMB-1971-005-9/}
}