14N NMR of tetrapropylammonium based crystals E. Dib, T. Mineva, P. Gaveau and B. Alonso Eur. Phys. J. Special Topics, 224 9 (2015) 1769-1773 Published online: 30 July 2015 DOI: 10.1140/epjst/e2015-02497-4