1. “The metastable Ni7xS6 and mixed Ni6x(S1-ySey)5 phases”. Liu Y, Norén L, Withers RL, Hadermann J, Van Tendeloo G, Garcia-Garcia J, Journal of solid state chemistry 170, 351 (2003).   http://doi.org/10.1016/S0022-4596(02)00123-8