⇒ The MacTutor History of Mathematics Archive
Galilei, Galileo, Discorsi e dimostrazioni matematiche intorno a due nuove scienze attenenti alla mecanica et i movimenti locali, Elsevirii, Leida 1638.
⇒ download from Gallica
Galilei, Galileo, Dialogues concerning two new sciences, Translated from the Italian and Latin by Herny Crew and Alfonso De Salvio, with an Introduction by Antonio Favaro, Macmillan, New York 1914
⇒ download from Internet Archive