@article{BUMI_1957_3_12_1_a2,
     author = {Bellman, Richard},
     title = {On the linear differential equations whose solutions are the products  of solutions of two given linear differential equations.},
     journal = {Bollettino della Unione matematica italiana},
     pages = {12--15},
     publisher = {mathdoc},
     volume = {Ser. 3, 12},
     number = {1},
     year = {1957},
     zbl = {0077.29101},
     mrnumber = {86960},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/BUMI_1957_3_12_1_a2/}
}