Knowles, R. (1981). Economic and Social Geography (Fourth Edition). ELSEVIER.
Lua i Stíl Chicago (17ú heag.)Knowles, R. Economic and Social Geography (Fourth Edition). ELSEVIER, 1981.
Lua MLA (8ú heag.)Knowles, R. Economic and Social Geography (Fourth Edition). ELSEVIER, 1981.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.