Columbia subject headings:
Architecture--Pennsylvania--Philadelphia--Guidebooks.
Buildings--Pennsylvania--Philadelphia--Guidebooks.
Philadelphia (Pa.)--Guidebooks.
Harvard subject headings:
Architecture--Pennsylvania--Philadelphia--Guidebooks.
Buildings--Pennsylvania--Philadelphia--Guidebooks.
Philadelphia (Pa.)--Buildings, structures, etc.--Guidebooks.
Philadelphia (Pa.)--Guidebooks.
Princeton subject headings:
Architecture--Pennsylvania--Philadelphia--Guidebooks.
Buildings--Pennsylvania--Philadelphia--Guidebooks.
Guidebooks.
Philadelphia (Pa.)--Buildings, structures, etc.--Guidebooks.
Philadelphia (Pa.)--Guidebooks.