“…It should be stressed, nevertheless, that a precise treatment of two-dimensional Ising models is often connected with considerable difficulties, which relate to the usage of sophisticated mathematical methods when applying them to more complex models describing, for instance, spin systems with interactions beyond nearest neighbors, 3-7 frustrated spin systems, [8][9][10] or higher-spin models with (or without) single-ion anisotropy and biquadratic interactions. [11][12][13][14][15][16][17][18][19][20][21][22] Up to now, exact results for Ising models on the square, 1 triangular and honeycomb, [23][24][25][26][27] kagomé, 28 extended kagomé, 29,30 bathroom-tile, [31][32][33][34][35] orthogonaldimer 36 and ruby 37 lattice, as well as on various irregular 2D lattices, such as Union Jack (centered square), [38][39][40][41][42][43][44] pentagonal, 45 square-kagomé, 46 or two topologically distinct square-hexagonal 47,48 lattices, have been obtained.…”