/images/1041385860215607387/1281534808714907699/trung-sinh-2011-dai-hoc-hang-hai-kiem-lau-985-chuong-1-sigma-nam-nhan.txt?ex=66dc11cc&is=66dac04c&hm=bf977977383f441f41af59c89e7a96ab9fe2312dc147083744f520d132b397d6&