Dear Dr. Duax,

We would like to express our gratitude to Graciela Diaz de Delgado and Miguel Delgado, of the CNDR-X, U. of Los Andes, Merida, Venezuela, for their efforts and support during our participation in the advance courses on single crystal X-ray diffraction held in Merida in November 1994.

We also appreciate the support offered by the Third World Academy of Sciences (TWAS) to facilitate contacts between research scientists in the South and their scientific institutions, under the TWAS South-South Fellowship Scheme; which help us to establish the contact between the Center of Pharmaceutical Chemistry in Havana and the U. of Los Andes.