“…Towards the conjecture that for any n -connected graph ) 1 ( n G , there are n ISTs rooted at an arbitrary vertex on G [1,2], it was only solved for 4 n [1,2,3,4], but remains open for 5 n . Thus, the results on special graphs are still the focus of researchers and many results have been obtained, such as hypercubes [5,6], crossed cubes [7], even networks [8], odd networks [9], folded hyper-stars [10], multidimensional torus networks [11], recursive circulant graphs [12], Gaussian networks [13], 2-chordal rings [14], and so on.…”