Guc, M.; Litvinchuk, A.P.; Levcenko, S.; Izquierdo-Roca, V.; Fontane, X.; Valakh, M.Y.; Arushanov, E.; Perez-Rodriguez, A. "Optical phonons in the wurtzstannite Cu2 ZnGeS4 semiconductor: Polarized Raman spectroscopy and first-principle calculations" Physical Review B - Condensed Matter and Materials Physics 89, 20, pp. - 2014 DOI: 10.1103/PhysRevB.89.205205