6Cohen, A. D. & Upton, T.A. Strategies in Responding to the New TOEFL Reading Tasks [R]. TOEFL Monograph Series 33 ETS. Princeton, NJ: Educational Testing Service. 2006:18.
7Flesch, R. A New Readability Yardstick [ J ]. Journal of Applied Psychology, 1948, 32 (3) :221 - 233.
8J. L. G6mez Pardo. Introduction to Cryptography with Maple [M]. Springer, 2013.
