Map of the County of Worcester ... by C. & J. Greenwood. Engraved by J. & C. Walker.
MLA
Map of the County of Worcester ... by C. & J. Greenwood. Engraved by J. & C. Walker. Greenwood & Co., 1830. https://collections.library.yale.edu/catalog/15350015.
APA, 6th edition
Map of the County of Worcester ... by C. & J. Greenwood. Engraved by J. & C. Walker. (1830). [Maps]. Greenwood & Co., https://collections.library.yale.edu/catalog/15350015.