Answer
References
Beers, S.N., & Lake, D.J. (1860). Map of the vicinity of Philadelphia [Map]. David Rumsey Historical Map Collection. https://searchworks.stanford.edu/view/10451036
Parenthetical citation: (Beers & Lake, 1860)
Narrative citation: Beers and Lake (1860) include inset business directories of Philadelphia, Germantown, Frankford, and Bridesburg in their map.
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