du Plessis, S. (1987). International Economics. ELSEVIER.
Lua i Stíl Chicago (17ú heag.)du Plessis, SPJ. International Economics. ELSEVIER, 1987.
Lua MLA (8ú heag.)du Plessis, SPJ. International Economics. ELSEVIER, 1987.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.