Starch INRA Hooper (Firm) & United States Travel Service. Research and Analysis Division. Belgium: A study of the international travel market. The Division, c1978.
Lua i Stíl Chicago (17ú heag.)Starch INRA Hooper (Firm) agus United States Travel Service. Research and Analysis Division. Belgium: A Study of the International Travel Market. [Washington: The Division, c1978.
Lua MLA (9ú heag.)Starch INRA Hooper (Firm) agus United States Travel Service. Research and Analysis Division. Belgium: A Study of the International Travel Market. The Division, c1978.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.