@article{10_4153_CJM_1994_008_1,
     author = {Xuebo, Luo},
     title = {Necessary and {Sufficient} {Conditions} for {Hypoellipticity} for a {Class} of {Convolution} {Operators}},
     journal = {Canadian journal of mathematics},
     pages = {212--224},
     year = {1994},
     volume = {46},
     number = {1},
     doi = {10.4153/CJM-1994-008-1},
     url = {http://geodesic.mathdoc.fr/articles/10.4153/CJM-1994-008-1/}
}