Oxidative Regeneration of Spent Molybdate and Tungstate Hydrotreating Catalysts Y. Yoshimura, T. Sato, H. Shimada, N. Matsubayashi, M. Imamura, A. Nishijima, S. Yoshitomi, T. Kameoka, and H. Yanase [Energy & Fuels, Vol.8, No.2, pp.435-445, 1994]