@ARTICLE{
author={Popovic Zoran V,Konstantinovic Milan J,Popov VN,Cantarero A,Dohcevic-Mitrovic Zorana D,Isobe M,Ueda Y},
year={2005},
title={Optical phonons in the NaTiSi2O6 oxide with S=1/2 spin chains},
journal={PHYSICAL REVIEW B},
volume={71},
number={22},
pages={-},
document_type={Article},
} 

@ARTICLE{
author={Popovic Zoran V,Konstantinovic Milan J,Gajic Rados B,Popov VN,Isobe M,Ueda Y,Moshchalkov VV},
year={2002},
title={Phonon dynamics in AV(2)O(5) (A=Na,Ca,Mg,Cs) oxides},
journal={PHYSICAL REVIEW B},
volume={65},
number={18},
pages={-},
document_type={Article},
}