@ARTICLE{
author={Andjelic Milica M,Ashraf Firouzeh,da Fonseca Carlos M,Simic Slobodan K},
year={2019},
title={Vertex types in some lexicographic products of graphs},
journal={LINEAR & MULTILINEAR ALGEBRA},
volume={67},
number={11},
pages={2282-2296},
document_type={Article},
} 

@ARTICLE{
author={Bamdad Hamidreza,Ashraf Firouzeh,Gutman Ivan},
year={2010},
title={Lower bounds for Estrada index and Laplacian Estrada index},
journal={APPLIED MATHEMATICS LETTERS},
volume={23},
number={7},
pages={739-742},
document_type={Article},
}