Ran Raz Omer Reingold Salil P. Vadhan Extracting all the Randomness and Reducing the Error in Trevisan's Extractors. 97-128 2002 65 J. Comput. Syst. Sci. 1 http://dx.doi.org/10.1006/jcss.2002.1824 db/journals/jcss/jcss65.html#RazRV02