Rome & its environs [cartographic material] : from a trigonometrical survey / by Sir William Gell ; engraved by J. Gardner.
MLA
Rome & Its Environs [Cartographic Material] : from a Trigonometrical Survey / by Sir William Gell ; Engraved by J. Gardner. Saunders & Otley, 1834. https://collections.library.yale.edu/catalog/15824439.
APA, 6th edition
Rome & its environs [cartographic material] : from a trigonometrical survey / by Sir William Gell ; engraved by J. Gardner. (1834). [Topographic maps]. Saunders & Otley, https://collections.library.yale.edu/catalog/15824439.