N. Kolev, V. N. Popov, M. N. Iliev, presented at the APS meeting 2003. “Raman study of CaFe2O4”.

A. P. Litvinchuk, C. L. Chen, N. Kolev, V. N. Popov, V. G. Hadjiev, M. N. Iliev, R. P. Bontchev and A. J. Jacobson, Phys. Stat. Solidi (a) 195, 453 (2003). "Optical properties of high-dielectric-constant CaCu3Ti4O12 film".

N. Kolev, R. P. Bontchev, A. J. Jacobson, V. N. Popov, V. G. Hadjiev, A. P. Litvinchuk and M. N. Iliev, Phys. Rev. B 66, art. No. 132102 (2002). "Raman spectroscopy of CaCu3Ti4O12".

N. Kolev, C. L. Chen, M. Gospodinov, R. P. Bontchev, V. N. Popov, A. P. Litvinchuk, M. V. Abrashev, V. G. Hadjiev and M. N. Iliev, Phys. Rev. B 66, art. No. 014101 (2002). "Raman spectroscopy of CaRuO3". Also presented at the APS meeting 2002.

N. Kolev, C. L. Chen, V. G. Hadjiev, A. P. Litvinchuk and M. N. Iliev, Phys. Stat. Solidi (a) 191, R7 (2002). "Microtwinning of epitaxial CaRuO3 thin films: A Raman study".

M. V. Abrashev, J. Backstrom, L. Borjesson, V. N. Popov, R. A. Chakalov, N. Kolev, R.-L. Meng and M. N. Iliev, Phys. Rev. B 65, 184301 (2002). "Raman spectroscopy of CaMnO3: mode assignment and relationship between Raman line intensities and structural distortions".

M. V. Abrashev, J. Backstrom, L. Borjesson, M. Pissas, N. Kolev and M. N. Iliev, Phys. Rev. B 64, 144429 (2001). "Raman spectroscopy of the charge- and orbital-ordered state in La0.5Ca0.5MnO3".

V. Ganev, N. Kolev, T. Troev, J. Serna, Comptes Rendus de l'Academie Bulgare des Sciences 52, 3-4, 25 (1999). "Study of the reliability of the multi-component analysis used in positron annihilation lifetime spectroscopy".