Ismo Hakala, Juha Kortelainen On the System of word equations x^i_1 x^i_2 ... x^i_m = y^i_1 y^i_2 ...y^i_n (i=1, 2, ...) in a Free Monoid. [Citation Graph (0, 0)][DBLP] Acta Inf., 1997, v:34, n:3, pp:217-230 [Journal]
Ismo Hakala Efficient Algorithms for Deciding the Morphism Equivalence Problem for Regular, Linear and Context-Free Languages. [Citation Graph (0, 0)][DBLP] Elektronische Informationsverarbeitung und Kybernetik, 1993, v:29, n:4, pp:209-213 [Journal]