“…For the n-vertex k-tree T k n , if k = 1, then it is just a tree and the extremal properties of W (G), H(G), DD(G), ξ d (G), H A (G), and H M (G) of n-vertex tree can be referred to in [2], [9], [10], [12], [26], [40], [41]. On the other hand, T k n ∼ = K n for k n k + 1 and T k n ∼ = P k n ∼ = S k,n−k for n = k + 2.…”