@article{RM_1981_36_3_a14,
     author = {V. V. Kozlov},
     title = {On the instability of equilibrium in a~potential field},
     journal = {Trudy Matematicheskogo Instituta imeni V.A. Steklova},
     pages = {256--257},
     publisher = {mathdoc},
     volume = {36},
     number = {3},
     year = {1981},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/RM_1981_36_3_a14/}
}