1. R�o de la Loza L (1852) Discurso pronunciado por el catedr�tico de Qu�mica M�dica de la Escuela de Medicina (November 23, 1852). In: Noriega JM (compiler) (1911) Escritos de Leopoldo R�o de la Loza. Imprenta Escalante, M�xico, p 94
2. For a detailed review see: Joseph-Nathan P, Santillan RL (1989) The Chemistry of Perezone and its Consequences. In: Atta-ur-Rahman (ed) Studies in Natural Products Chemistry, vol 5, Structural Elucidation (Part B). Elsevier, Amsterdam, p 763
3. Ansch�tz R, Leather W (1885) Chem Ber18: 715
4. Walls F, Padilla J, Joseph-Nathan P, Giral F, Romo J (1965) Tetrahedron Lett21: 1577
5. Joseph-Nathan P, Mendoza V, Garc�a E (1977) Tetrahedron33: 1573