@article{PORMA_1966__25_3_114985,
     author = {Biesterfeldt, H.J. jr.},
     title = {Summability of series of polynomial solutions to a hypoelliptic equation},
     journal = {Portugaliae mathematica},
     pages = {147--164},
     publisher = {mathdoc},
     volume = {25},
     number = {3},
     year = {1966},
     mrnumber = {0233991},
     zbl = {0173.12201},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/PORMA_1966__25_3_114985/}
}