@article{DAN_1992_324_2_a16,
     author = {Ya. N. Fel'd},
     title = {On the quadratic lemma in electrodynamics},
     journal = {Doklady Akademii Nauk},
     pages = {321--324},
     publisher = {mathdoc},
     volume = {324},
     number = {2},
     year = {1992},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1992_324_2_a16/}
}