Torrens, H. S.. (2006) “The geological work of Gregory Watt, his travels with William Maclure in Italy (1801–1802), and Watt's "proto-geological" map of Italy (1804)”, The Origins of Geology in Italy, Geological Society of America 411, p. 179–197. doi:10.1130/2006.2411(11). ISBN 0-8137-2411-2.
McCabe, Joseph (1945). A Biographical Dictionary of Ancient, Medieval, and Modern Freethinkers. Haldeman-Julius Publications. Alirita 17a de Aŭgusto 2012 . “He made such improvement in the crude steam-engine that had been invented before his time that he is usually described as the inventor. "His many and most valuable inventions must always place him among the leading benefactors of mankind," says the account of him in the Dictionary of National Biography. He was an accomplished man. He knew Greek, Latin, French, German and Italian and was very friendly with the great freethinking French scientists. Andrew Carnegie has written a life of him and describes him as a deist who never went to church.”.
