@article{DAN_1966_171_5_a6,
     author = {A. Yu. Levin},
     title = {Classification of no-oscillation cases for equation $\ddot{x}+p(t)\dot{x}+q(t)x=0$ where $q (t)$ is of constant sign},
     journal = {Doklady Akademii Nauk},
     pages = {1037--1040},
     publisher = {mathdoc},
     volume = {171},
     number = {5},
     year = {1966},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1966_171_5_a6/}
}