| 1. | Los viajes de los españoles al extranjero en 1987 / Secretaría General de TurismoData Publicação: 1988 Col.autor: Espanha. Secretaría General de Turismo |  | |
| 2. | The 1988 holiday survey: an independent survey into customer satisfaction with package holidays / ABTA - Association of British Travel AgentsData Publicação: 1988 Col.autor: ABTA - Association of British Travel Agents | | |
| 3. | International tourism forecasts to 1999 / by Anthony EdwardsAutor: Edwards, Anthony Data Publicação: 1988 Co col. autor sec.: EIU | | |