@article{JOLT_2013_23_3_a11,
     author = {Xiaojing Feng and Pengcheng Niu},
     title = {Interior {Regularity} for {Degenerate} {Elliptic} {Equations} with {Drift} on {Homogeneous} {Groups}},
     journal = {Journal of Lie Theory},
     pages = {803--825},
     year = {2013},
     volume = {23},
     number = {3},
     url = {http://geodesic.mathdoc.fr/item/JOLT_2013_23_3_a11/}
}