@ARTICLE{
author={Ginosar Yuval,Gutman Ivan,Mansour Toufik,Schork Matthias},
year={2008},
title={Estrada index and Chebyshev polynomials},
journal={CHEMICAL PHYSICS LETTERS},
volume={454},
number={4-6},
pages={145-147},
document_type={Article},
} 

@ARTICLE{
author={Gutman Ivan,Radenkovic Slavko,Furtula Boris,Mansour Toufik,Schork Matthias},
year={2007},
title={Relating Estrada index with spectral radius},
journal={JOURNAL OF THE SERBIAN CHEMICAL SOCIETY},
volume={72},
number={12},
pages={1321-1327},
document_type={Article},
}