BIBCYT http://bibcyt.ucla.edu.ve/cgi-win/be_alex.exe?Ultimo&Nombrebd=BIBCYT UCLA - Biblioteca de Ciencias y Tecnologia Felix Morales Bueno Liang, Chao P Principal Liu, Geng P Principal Sun , Wenxiang P Principal Approximation properties on invariant measure and Oseledec splitting in non-uniformly hyperbolic systems March 2009 pp. 1543-1579