Andrzej Ehrenfeucht, Grzegorz Rozenberg. On the (Generalized) Post Correspondence Problem with Lists of Length 2. In Shimon Even, Oded Kariv, editors, Automata, Languages and Programming, 8th Colloquium, Acre (Akko), Israel, July 13-17, 1981, Proceedings. Volume 115 of Lecture Notes in Computer Science, pages 408-416, Springer, 1981.
Abstract is missing.