External electric and magnetic field effects on the polaron in a wurtzite nitride nanowire embedded in a nonpolar matrixAnna L. Asatryan, Ashot H. Movsisyan and Arshak L. VartanianEur. Phys. J. B, 94 3 (2021) 70DOI: https://doi.org/10.1140/epjb/s10051-021-00071-5