@article{10_2307_121104,
     author = {Mikhail V. Safonov and Yu Yuan},
     title = {Doubling properties for second order parabolic equations.},
     journal = {Annals of mathematics},
     year = {1999},
     volume = {150},
     number = {1},
     doi = {10.2307/121104},
     zbl = {1157.35391},
     url = {http://geodesic.mathdoc.fr/articles/10.2307/121104/}
}