@ARTICLE{
author={Djurdjevic Jelena,Gutman Ivan,Ponec Robert},
year={2009},
title={Verifying the PCP-rule by five-center bond indices},
journal={JOURNAL OF THE SERBIAN CHEMICAL SOCIETY},
volume={74},
number={5},
pages={549-554},
document_type={Article},
} 

@ARTICLE{
author={Ponec Robert,Fias Stijn,Van Damme Sofie,Bultinck Patrick,Gutman Ivan,Stankovic Sonja},
year={2009},
title={The close relation between cyclic delocalization, energy effects of cycles and aromaticity},
journal={COLLECTION OF CZECHOSLOVAK CHEMICAL COMMUNICATIONS},
volume={74},
number={1},
pages={147-166},
document_type={Article},
}