[1] J. Amalorpava Jerline and L. Benedict Michaelraj, On a conjecture of harmonic index and diameter of graphs, Kragujevac J. Math. 40 (2016), no. 1, 73–78.
[2] J. Amalorpava Jerline and L. Benedict Michaelraj, On harmonic index and diameter of unicyclic graphs, Iranian J. Math. Sci. Inform. 11 (2016), no. 1, 115–122.
[3] H. Deng, S. Balachandran, S.K. Ayyaswamy, and Y.B. Venkatakrishnan, On the harmonic index and the chromatic number of a graph, Discrete Appl. Math. 161 (2013), no. 16-17, 2740–2744.
[4] H. Deng, S. Balachandran, S.K. Ayyaswamy, and Y.B. Venkatakrishnan, On harmonic indices of trees, unicyclic graphs and bicyclic graphs, Ars Combin. 130 (2017), 239–248.
[5] S. Fajtlowicz, On conjectures of graffiti-ii, Congr. Numer 60 (1987), 187–197.
[6] O. Favaron, M. Mahéo, and J.-F. Saclé, Some eigenvalue properties in graphs (conjectures of graffitiii), Discrete Math. 111 (1993), no. 1-3, 197–220.
[7] B. Furtula, I. Gutman, and M. Dehmer, On structure-sensitivity of degree-based topological indices, Appl. Math. Comput. 219 (2013), no. 17, 8973–8978.
[8] I. Gutman, Degree-based topological indices, Croat. Chem. Acta 86 (2013), no. 4, 351–361.
[9] I. Gutman, L. Zhong, and K. Xu, Relating the abc and harmonic indices, J. Serb. Chem. Soc. 79 (2014), no. 5, 557–563.
[10] Y. Hu and X. Zhou, On the harmonic index of the unicyclic and bicyclic graphs, WSEAS Trans. Math. 12 (2013), no. 6, 716–726.
[11] A. Ilic, Note on the harmonic index of a graph, Ars Combin. 128 (2016), 295–299.
[12] M. Iranmanesh and M. Saheli, On the harmonic index and harmonic polynomial of caterpillars with diameter four, Iranian J. Math. Chem. 6 (2015), no. 1, 41–49.
[13] L.V. Jian-Bo, J. Li, and S.W. Chee, The harmonic index of unicyclic graphs with given matching number, Kragujevac J. Math. 38 (2014), no. 1, 173–183.
[14] J. Li and W.C. Shiu, The harmonic index of a graph, Rocky Mountain J. Math. 44 (2014), no. 5, 1607–1620.
[15] J. Liu, On harmonic index and diameter of graphs, J. Appl. Math. Phys. 1 (2013), no. 3, 5.
[16] , On the harmonic index of triangle-free graphs, Appl. Math. 4 (2013), no. 8, 1204–1206.
[17] , Harmonic index of dense graphs, Ars Combin. 120 (2015), 293–304.
[18] J. Liu and Q. Zhang, Remarks on harmonic index of graphs, Util. Math. 88 (2012), 281–285.
[19] R. Wu, Z. Tang, and H. Deng, A lower bound for the harmonic index of a graph with minimum degree at least two, Filomat 27 (2013), no. 1, 51–55.
[20] R. Wu, Z. Tang, and H. Deng, On the harmonic index and the girth of a graph, Util. Math. 91 (2013), 65–69.
[21] X. Xu, Relationships between harmonic index and other topological indices, Appl. Math. Sci 6 (2012), no. 41, 2013–2018.
[22] L. Zhong, The harmonic index for graphs, Appl. Math. Lett. 25 (2012), no. 3, 561–566.
[23] L. Zhong, The harmonic index on unicyclic graphs, Ars Combin. 104 (2012), 261–269.
[24] L. Zhong, The harmonic index for unicyclic and bicyclic graphs with given matching number, Miskolc Math. Notes 16 (2015), no. 1, 587–605.
[25] L. Zhong and Q. Cui, The harmonic index for unicyclic graphs with given girth, Filomat 29 (2015), no. 4, 673–686.
[26] L. Zhong and K. Xu, The harmonic index for bicyclic graphs, Util. Math. 90 (2013), 23–32.
[27] , Inequalities between vertex-degree-based topological indices, MATCH Commun. Math. Comput. Chem. 71 (2014), no. 3, 627–642.
[28] Y. Zhu and R. Chang, Minimum harmonic indices of trees and unicyclic graphs with given number of pendant vertices and diameter, Util. Math. 93 (2014), 365–374.
[29] Y. Zhu and R. Chang, On the harmonic index of bicyclic conjugated molecular graphs, Filomat 28 (2014), no. 2, 421–428.
[30] Y. Zhu, R. Chang, and X. Wei, The harmonic index on bicyclic graphs, Ars Combin. 110 (2013), 97–104.