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@article{PIM_1977_N_S_21_35_a28, author = {B. Stankovi\'c}, title = {Approximate {Solutions} {Of} {The} {Operator} {Linear} {Differential} {Equation} {I}}, journal = {Publications de l'Institut Math\'ematique}, pages = {185 }, publisher = {mathdoc}, volume = {_N_S_21}, number = {35}, year = {1977}, url = {http://geodesic.mathdoc.fr/item/PIM_1977_N_S_21_35_a28/} }
B. Stanković. Approximate Solutions Of The Operator Linear Differential Equation I. Publications de l'Institut Mathématique, _N_S_21 (1977) no. 35, p. 185 . http://geodesic.mathdoc.fr/item/PIM_1977_N_S_21_35_a28/