Correspondence from contributors 1958 1973-1975

First period: Issues 1-40 1973-05-1976-08

Second period: Issues 41-53 1986-04-1987-04

Third period: Issues 54-80 1987-10-1990-06

Fourth period ( Adios Crisis, Fin de Siglo): Issues 1-18 1987-07-1988-12