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@article{DE_1966_2_10_a5, author = {N. P. Erugin}, title = {On the theory of canonical systems}, journal = {Differencialʹnye uravneni\^a}, pages = {1317--1332}, publisher = {mathdoc}, volume = {2}, number = {10}, year = {1966}, language = {ru}, url = {http://geodesic.mathdoc.fr/item/DE_1966_2_10_a5/} }
N. P. Erugin. On the theory of canonical systems. Differencialʹnye uravneniâ, Tome 2 (1966) no. 10, pp. 1317-1332. http://geodesic.mathdoc.fr/item/DE_1966_2_10_a5/