SPENCER, D. E. (1990). Studi guide parkin economics. Addison-Wesley Pub.
Lua i Stíl Chicago (17ú heag.)SPENCER, David E. Studi Guide Parkin Economics. Reading: Addison-Wesley Pub, 1990.
Lua MLA (9ú heag.)SPENCER, David E. Studi Guide Parkin Economics. Addison-Wesley Pub, 1990.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.