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@article{PIM_1952_S_S_IV_04_a12, author = {J. Popken}, title = {An {Arithmetical} {Theorem} {Concerning} {Linear} {Differential} - {Difference} {Equations}}, journal = {Publications de l'Institut Math\'ematique}, pages = {121 }, publisher = {mathdoc}, volume = {_S_S_IV}, number = {04}, year = {1952}, url = {http://geodesic.mathdoc.fr/item/PIM_1952_S_S_IV_04_a12/} }
J. Popken. An Arithmetical Theorem Concerning Linear Differential - Difference Equations. Publications de l'Institut Mathématique, _S_S_IV (1952) no. 04, p. 121 . http://geodesic.mathdoc.fr/item/PIM_1952_S_S_IV_04_a12/