Columbia subject headings:
Historical Society of Pennsylvania--Catalogs.
Manuscripts, American--Pennsylvania--Philadelphia--Catalogs.
Manuscripts--Pennsylvania--Catalogs.
Pennsylvania--History--Manuscripts--Catalogs.
Pennsylvania--History--Sources--Bibliography--Catalogs.
Pennsylvania--History--Sources--Bibliography.
United States--History--Sources--Bibliography.
Harvard subject headings:
Princeton subject headings:
Manuscripts--Pennsylvania--Philadelphia--Catalogs.
Pennsylvania--History--Sources--Bibliography.