Spain and Portugal [cartographic material].
MLA
Blackie, W. G. (Walter Graham), 1816-1906. Spain and Portugal [cartographic material].. BRBL_00188. [1850]. https://collections.library.yale.edu/catalog/15487270.
APA, 6th edition
Blackie, W. G. (Walter Graham), 1816-1906. (["BRBL_00188"])([1850])[Spain and Portugal [cartographic material].]. https://collections.library.yale.edu/catalog/15487270.