S. Mao, R.E. Boltnev, V.V. Khmelenko, and D.M. Lee, ESR studies of nitrogen atoms stabilized in aggregates of krypton–nitrogen nanoclusters immersed in superfluid helium, Low Temp. Phys. 38, (2012) [Fiz. Nizk. Temp. 38, 1313-1319, (2012)] DOI: https://doi.org/10.1063/1.4765092.