@ARTICLE{
author={Dobrynin AA,Gutman Ivan,Klavzar Sandi,Igert P},
year={2002},
title={Wiener index of hexagonal systems},
journal={ACTA APPLICANDAE MATHEMATICAE},
volume={72},
number={3},
pages={247-294},
document_type={Review},
} 

@ARTICLE{
author={Dobrynin AA,Entringer R,Gutman Ivan},
year={2001},
title={Wiener index of trees: Theory and applications},
journal={ACTA APPLICANDAE MATHEMATICAE},
volume={66},
number={3},
pages={211-249},
document_type={Review},
}