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@article{FAA_2011_45_4_a0, author = {A. A. Agrachev}, title = {On the space of symmetric operators with multiple ground states}, journal = {Funkcionalʹnyj analiz i ego prilo\v{z}eni\^a}, pages = {1--15}, publisher = {mathdoc}, volume = {45}, number = {4}, year = {2011}, language = {ru}, url = {http://geodesic.mathdoc.fr/item/FAA_2011_45_4_a0/} }
A. A. Agrachev. On the space of symmetric operators with multiple ground states. Funkcionalʹnyj analiz i ego priloženiâ, Tome 45 (2011) no. 4, pp. 1-15. http://geodesic.mathdoc.fr/item/FAA_2011_45_4_a0/