In 1977 Boetti published the volume Classifying, the thousand longest rivers in the world, in which he collects the complete classification, from 1970 to 1973 together with Annemarie Sauzeau, of the 1000 longest rivers in the world. In 1975, projects were also born for the creation of two large monochrome tapestries entitled 'The thousand longest rivers in the world', in which the names of the rivers appear written without interruption, imitating the dotted characters of electronic calculators, similar to the Braille writing. The two tapestries, one white and the other green, will be made in 1979. On the occasion of the Turin exhibition organized by the Franz Paludetto Gallery, the green tapestry has been translated into a letterpress edition of 99 signed copies, and in a series of posters used to advertise the exhibition printed in offset, without circulation. Defects.