@article{10_1090_S0894_0347_1989_0955604_8,
     author = {Fefferman, R.},
     title = {A criterion for the absolute continuity of the harmonic measure associated with an elliptic operator},
     journal = {Journal of the American Mathematical Society},
     pages = {127--135},
     year = {1989},
     volume = {02},
     number = {1},
     doi = {10.1090/S0894-0347-1989-0955604-8},
     url = {http://geodesic.mathdoc.fr/articles/10.1090/S0894-0347-1989-0955604-8/}
}