Penjerdel (Corporation). (1961). Historical development of local government in the Penjerdel region. Pennsylvania Economy League (Eastern Division).
Lua i Stíl Chicago (17ú heag.)Penjerdel (Corporation). Historical Development of Local Government in the Penjerdel Region. Philadelphia?: Pennsylvania Economy League (Eastern Division), 1961.
Lua MLA (8ú heag.)Penjerdel (Corporation). Historical Development of Local Government in the Penjerdel Region. Pennsylvania Economy League (Eastern Division), 1961.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.