Shunsuke Inenaga Ayumi Shinohara Masayuki Takeda Setsuo Arikawa Compact directed acyclic word graphs for a sliding window. 33-51 2004 2 J. Discrete Algorithms 1 http://dx.doi.org/10.1016/S1570-8667(03)00064-9 db/journals/jda/jda2.html#InenagaSTA04