“…Hundreds of papers and a few books are devoted to this topological index. "Details about the chemical applicability and mathematical properties of this index can be found in the surveys, [7,8] recent papers, [9][10][11] and/or related references cited therein.In 1998, Estrada et al [12] devised the following modified version of the Randić index [and called it as atom-bond connectivity (ABC) index]:for predicting the heats of formation of alkanes. Due to chemical applicability of the ABC index, [12][13][14] numerous publications concerning mathematical properties of this index (particularly, related to the characterization of the tree(s) with minimum ABC index among all n-vertex trees) have been and are being appeared, see for example, the surveys, [7,15] recent papers, [16][17][18][19] and/or related references cited therein.…”