1. R. Entringer, Distance in graphs: Trees, J. Combin. Math. Combin. Comput. 24
(1997) 65–84.
2. I. Gutman, S. Klavžar, B. Mohar (Eds), Fifty years of the Wiener index, MATCH
Commun. Math. Comput. Chem. 35 (1997) 1–259.
3. H. Hosoya, Topological Index, A Newly Proposed Quantity Characterizing the
Topological Nature of Structural Isomers of Saturated Hydrocarbons, Bull. Chem.
Soc. Jpn. 44 (1971) 2332–2339.
4. H. Wiener, Structural Determination of Paraffin Boiling Points, J. Am. Chem. Soc.
69 (1947) 17–20.
5. I. Gutman, A formula for the Wiener number of trees and its extension to graphs
containing cycles, Graph Theory Notes N.Y. 27 (1994) 9–15.
6. S. Klavžar, A. Rajapakse, I. Gutman, The Szeged and the Wiener index of graphs,
Appl. Math. Lett. 9 (1996) 45–49.
7. P. V. Khadikar, On a Novel structural descriptor PI, Nat. Acad. Sci. Lett. 23 (2000)
113–118.
8. P. V. Khadikar. S. Karmakar and V. K. Agrawal, Relationship and relative
correction potential of the Wiener, Szeged and PI Indices, Nat. Acad. Sci. Lett. 23
(2000) 165–170.
9. H. P. Schultz, T. P. Schultz, Topological organic chemistry. 3. Graph theory, Binary
and Decimal Adjacency Matrices, and Topological indices of Alkanes, J. Chem. Inf.
Comput. Sci. 31 (1991) 144–147.
10. H. P. Schultz, T. P. Schultz, Topological organic chemistry. 6. Theory and
topological indices of cycloalkanes, J. Chem. Inf. Comput. Sci. 33 (1993) 240–244.
11. I. Gutman, Selected properties of the Schultz molecular topological index, J. Chem.
Inf. Comput. Sci. 34 (1994) 1087–1089.
12. I. Gutman, Y. N. Yeh, S. L. Lee, Y. L. Luo, Some recent results in the theory of the
Wiener number, Indian J. Chem. 32 (1993) 651–661.
13. M. Randić, Novel molecular descriptor for structure–property studies, Chem. Phys.
Lett. 211 (1993) 478–483.
14. D. J. Klein, I. Lukovits, I. Gutman, On the definition of the hyper–Wiener index for
cycle-containing structures, J. Chem. Inf. Comput. Sci. 35 (1995) 5052.
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