Voir la notice de l'article provenant de la source Math-Net.Ru
@article{DE_1976_12_7_a0, author = {V. V. Amel'kin and V. \`E. Zhavnerchik}, title = {Periodic solutions of certain second order equations}, journal = {Differencialʹnye uravneni\^a}, pages = {1147--1150}, publisher = {mathdoc}, volume = {12}, number = {7}, year = {1976}, language = {ru}, url = {http://geodesic.mathdoc.fr/item/DE_1976_12_7_a0/} }
V. V. Amel'kin; V. È. Zhavnerchik. Periodic solutions of certain second order equations. Differencialʹnye uravneniâ, Tome 12 (1976) no. 7, pp. 1147-1150. http://geodesic.mathdoc.fr/item/DE_1976_12_7_a0/