共 7 条
[4]
Chow W-L., 1939, Math. Ann, V117, P98, DOI [10.1007/BF01450011, DOI 10.1007/BF01450011]
[6]
HYPOELLIPTIC 2ND ORDER DIFFERENTIAL EQUATIONS
[J].
ACTA MATHEMATICA UPPSALA,
1967, 119 (3-4)
:147-&