@article{DAN_1990_313_6_a25,
     author = {V. L. Krupenin},
     title = {Transformation of the vibration modes of a string that interacts
},
     journal = {Doklady Akademii Nauk},
     pages = {1390--1394},
     publisher = {mathdoc},
     volume = {313},
     number = {6},
     year = {1990},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1990_313_6_a25/}
}