1. A generic membrane computing-based Sudoku solver;Deodhare,2014
2. Complexity and completeness of finding another solution and its application to puzzles;Takayuki;IEICE Trans. Fundam. Electron. Commun. Comput. Sci.,2003
3. M. Perez, T. Marwala, Stochastic optimization approaches for solving Sudoku (2008) (arXiv preprint arXiv:0805.0697).
4. http://www.websudoku.com (accessed 15.07.15).
5. http://en.top-sudoku.com/hexadoku/choose-hexadoku-grid.php (accessed 20.11.15).