1. Ovalles C, Hamana A, Bolivar R, Morales A. US Patent 5,269,909; 1993.
2. Upgrading of extra-heavy crude oil by direct use of methane in the presence of water
3. Ovalles C, Hamana A, Bolivar R, Morales A. Proceeding of the 10th Conference of UNITAR, Houston, Texas; Feb 1995.
4. Proceedings of the 11th International Congress. Catalysis: 40th Anniversary;Morales,1996