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@article{SEMR_2009_6_a26, author = {V. V. Ivanov}, title = {Dynamic quadrangles and isochronous oscillations}, journal = {Sibirskie \`elektronnye matemati\v{c}eskie izvesti\^a}, pages = {381--384}, publisher = {mathdoc}, volume = {6}, year = {2009}, language = {ru}, url = {http://geodesic.mathdoc.fr/item/SEMR_2009_6_a26/} }
V. V. Ivanov. Dynamic quadrangles and isochronous oscillations. Sibirskie èlektronnye matematičeskie izvestiâ, Tome 6 (2009), pp. 381-384. http://geodesic.mathdoc.fr/item/SEMR_2009_6_a26/