Haim H. Permuter Paul Cuff Benjamin Van Roy Tsachy Weissman Capacity of the Trapdoor Channel With Feedback. 3150-3165 2008 54 IEEE Transactions on Information Theory 7 http://dx.doi.org/10.1109/TIT.2008.924681 db/journals/tit/tit54.html#PermuterCRW08