@article{PORMA_1970__29_1_115103,
     author = {Al-Bassam, M.A.},
     title = {On the existence of series solution of differential equations of generalized order},
     journal = {Portugaliae mathematica},
     pages = {5--11},
     publisher = {mathdoc},
     volume = {29},
     number = {1},
     year = {1970},
     mrnumber = {0291526},
     zbl = {0219.34009},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/PORMA_1970__29_1_115103/}
}