@article{AM2_1973__9_136339,
     author = {CHARLES H. FRANKE},
     title = {Reducible {Linear} {Difference} {Operators}},
     journal = {Aequationes mathematicae},
     pages = {136--144},
     publisher = {mathdoc},
     volume = {9},
     year = {1973},
     zbl = {0276.12102},
     url = {http://geodesic.mathdoc.fr/item/AM2_1973__9_136339/}
}