THz sources based on frequency conversion of multi-line molecular lasers in nonlinear crystals and on optically pumped molecular lasersA. A. Ionin, I. O. Kinyaevskiy, Yu. M. Klimachev, A. A. Kotkov and A. M. SagitovaEPJ Web Conf., 195 (2018) 03004DOI: https://doi.org/10.1051/epjconf/201819503004