1. [1] T. Yato and T. Seta, “Complexity and completeness of finding another solution and its application to puzzles,” IEICE Trans. Fundamentals, vol.E86-A, no.5, pp.1052-1060, May 2003.
2. [2] E.D. Demaine, S. Hohenberger, and D. Liben-Nowell, “Tetris is hard, even to approximate,” CoRR, vol.cs.CC/0210020, 2002. (http://arxiv.org/abs/cs.CC/0210020).
3. [3] H. Muta, “PUYOPUYO is NP-complete (in Japanese),” IEICE Technical Report, COMP2005-14, http://ci.nii.ac.jp/naid/10016436795/, 2005.
4. [4] T. Matsukane and Y. Takenaga, “NP-completeness of maximum chain problem on generalized PUYOPUYO (in Japanese),” IEICE Trans. Inf. & Syst. (Japanese Edition), vol.J89-D, no.3, pp.405-413, March 2006.
5. [5] G. Aloupis, E.D. Demaine, and A. Guo, “Classic Nintendo games are (NP-)hard,” arXiv.org, http://arxiv.org/abs/1203.1895v1, 2012.