Shachar Lovett Omer Reingold Luca Trevisan Salil P. Vadhan Pseudorandom Bit Generators That Fool Modular Sums. 615-630 2009 APPROX-RANDOM http://dx.doi.org/10.1007/978-3-642-03685-9_46 conf/approx/2009 db/conf/approx/approx2009.html#LovettRTV09