1. Costello, M.J.: The greatest puzzles of all time. Prentice-Hall, Englewood Cliffs (1988)
2. Lecture Notes in Computer Science;E.D. Demaine,2003
3. Kaye, R.: Minesweeper is NP-complete. Mathematical Intelligencer 22, 9–15 (2000)
4. Culberson, J.: Sokoban is PSPACE-complete. In: Proceedings of the International Conference on Fun with Algorithms, Carleton Scientific, pp. 65–76 (1998)
5. Yato, T., Seta, T.: Complexity and completeness of finding another solution and its application to puzzles. IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences 86, 1052–1060 (2003)