On systems of word equations over three unknowns with at most six occurrences of one of the unknowns.

Elena Czeizler Wojciech Plandowski On systems of word equations over three unknowns with at most six occurrences of one of the unknowns. 2889-2909 2009 410 Theor. Comput. Sci. 30-32 http://dx.doi.org/10.1016/j.tcs.2009.01.023 db/journals/tcs/tcs410.html#CzeizlerP09