@article{DE_1969_5_10_a18,
     author = {P. Ya. Kirik},
     title = {The orthogonality of the derivatives of the eigenforms of the vibrations of an inhomogeneous rod},
     journal = {Differencialʹnye uravneni\^a},
     pages = {1899--1900},
     publisher = {mathdoc},
     volume = {5},
     number = {10},
     year = {1969},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1969_5_10_a18/}
}