In 1618 Milanese scholar Girolamo Sirtori (Hieronymus Sirturus) published the first book on the telescope: Telescopium: sive ars perficiendi novum illud Galilaei virorium instrumentum ad sydera, issued from Frankfurt at the press of Paul Jacob. Sirtori had written the book in 1612, only 4 years after the telescope was invented. The book contained a complete set of instructions, and diagrams, for building a refracting telescope.
van Helden, Dupré, van Gent, & Zuidervaart (eds.) The Origins of the Telescope (2010) 3, and numerous other references.
