E. Savchenko, I. Khyzhniy, and V. Bondybey<sup>2, New trends in spectroscopy of solid nitrogen (Topical Review), Low Temp. Phys. 45, (2019) [Fiz. Nizk. Temp. 45, 1144-1157, (2019)] DOI: https://doi.org/10.1063/1.5121267.