10 A. C. Kaporis, L. M. Kirousis, Y. C. Stamatiou, M. Vamvakari, and M. Zito, Discrete Appl. Math. 155 , 1525 (2007), ISSN 0166-218X. 11 E. Brezin and J. Zinn-Justin, Nucl. Phys. B 257 , 867 (1985). 12 R. H¨ aggkvist, A. Rosengren, P. H. Lundow, K. Markstr¨ om, D. Andr´en, and P. Kundrotas, Adv. Phys. 56 , 653 (2007). 13 R. Baxter, Exactly solved models in statistical mechanics (Academic Press, 1982). 14 R. H¨ aggkvist and P. H. Lundow, J. Statist. Phys. 108 , 429 (2002), See also http://www.theophys.kth.se/~phl . 15 R. H¨ aggkvist, A. Rosengren, D. Andr´en, P. Kundrotas, P. H. Lundow, and K. Markstr¨ om, J. Statist. Phys. 114 , 455 (2004). 16 P. H. Lundow and K. Markstr¨ om, Cent. Eur. J. Phys. 7 , 490 (2009). 17 L. Onsager, Phys. Rev. (2) 65 , 117 (1944). 18 C. N. Yang, Phys. Rev. 85 , 808 (1952). 19 D. B. Abraham, Eur. Phys. J. B 19 , 349 (1978). 20 A. Rosengren, J. Phys. A 19 , 1709 (1986). 21 P. Y. Lai and K. K. Mon, Phys. Rev. B 41 , 9257 (1990). 22 P. H. Lundow and K. Markstr¨ om, Phys. Rev. E 80 , 031104 (2009). 23 J. Cardy, Scaling and renormalization in statistical physics , vol. 5 of Cambridge Lecture Notes in Physics (Cambridge University Press, Cambridge, 1996). 24 E. Luijten, K. Binder, and H. W. J. Bl¨ ote, Eur. Phys. J. B 9 , 289 (1999). 25 K. K. Mon, Europhys. Lett. 34 , 399 (1996). 51