NMR study of non-equilibrium state of fullerene C60 in N-methyl-2-pyrrolidone - O. B. Karpenko; V. V. Trachevskyi; O. V. Filonenko; V. V. Lobanov; M. V. Avdeiev; T. V. Tropin; O. A. Kyzyma; S. V. Snehir (Ukrainian Journal of Physics, 2012)