Frey, B. S. (1978). Modern political economy. Robertson.
Lua i Stíl Chicago (17ú heag.)Frey, Bruno S. Modern Political Economy. Oxford: Robertson, 1978.
Lua MLA (9ú heag.)Frey, Bruno S. Modern Political Economy. Robertson, 1978.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.