[1] Geller D. Liouville’s theorem for homogeneous groups. Comm P D E, 1983, 8(15): 1665-1677
[2] Xuebo L. Liouville’s theorem for homogeneous differntial operators. Comm P D E, 1997, 22(11/12):
1837-1848
[3] Bonfiglioli A, Lanconelli E. Liouville-type theorem for real sub-Laplacians. Manuscripta Math, 2001, 105:
111-124
[4] Nagel A, Stein E M. Lecture on pseudo-differential operators. 7-8. Princeton Univ Press, 1979
[5] G˙arding L. Some Points of Analysis and Their History (Translated into Chinese by Li Daqian & Zhou
Zhengliang). Beijing: Higher Education Press, 2001. 89-94
[6] Chen Qingyi. General Linear Partial Differential Equations. Beijing: Higher Education Press, 1987
[7] Xuebo L, Chunxiong H. Hypoelliptic convolution oprators and Rockland condition. Science in China,
1996, 39(10): 1025-1033
[8] Rothschild L P. A remark on hypoellipticity of homogeneous invariant differential operators on nilpotent
Lie groups. Comm P D E, 1983, 8(15): 1679-1682
|