Rakhmatullaev, M. M. “On Weakly Periodic Gibbs Measures for the Potts Model With External Field on the Cayley Tree”. Ukrains’kyi Matematychnyi Zhurnal, Vol. 68, no. 4, Apr. 2016, pp. 529-41, https://umj.imath.kiev.ua/index.php/umj/article/view/1858.