Mimeographed letters with original signatures and some with clarifying written notes of the following types: 1) designations (Associated Protector of the University Federation, Member of the Assessing Commission of the National Institute of Technology, Member of the Argentine Association for the Progress of the Sciences, Member of the Argentine Center of Engineers, Titled Academic and President of the National Academy of Exact, Physical, and Natural Sciences); 2) correspondence with Argentine physicists and astronomers (Guido Beck, Enrique Gaviola, Ricardo Platzeck, Enrique Loedel, Dami n Canals Frau, Jos Wrschmidt, etc.); 3) correspondence with foreign physicists (Leon Fourvel Figleau, J. Costa Ribeiro, Walter Schtzer, Manuel Bellartz, Alfredo Baos, V. Lussatti, etc.); 4) correspondence emanating from the Argentine Association of Physics during the Presidencies of Guido Beck and Enrique Gaviola containing opions, concepts, and discussion of scientific work; 6) important correspondence emanating from foreign and international organizations, such as Brazilian Center for Physics Research, American Institute of Physics, National Center for Scientific Research (Center Nationale de la Recherche Scientifique).