TY  - JOUR
AU  - Shing-Tung Yau
AU  - Huai-Dong Cao
TI  - Gradient estimates, Harnack inequalities and estimates for heat kernels of the sum of squares of vector fields.
JO  - Mathematische Zeitschrift
PY  - 1992
SP  - 485
EP  - 504
VL  - 211
IS  - 3
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/MZ_1992__211_3_174454/
ID  - MZ_1992__211_3_174454
ER  -