Starch INRA Hooper (Firm) & United States Travel Service. Research and Analysis Division. Belgium: A study of the international travel market. The Division, c1978.
Chicago-referens (17:e uppl.)Starch INRA Hooper (Firm) och United States Travel Service. Research and Analysis Division. Belgium: A Study of the International Travel Market. [Washington: The Division, c1978.
MLA-referens (9:e uppl.)Starch INRA Hooper (Firm) och United States Travel Service. Research and Analysis Division. Belgium: A Study of the International Travel Market. The Division, c1978.
Varning: dessa hänvisningar är inte alltid fullständigt riktiga.