Reglamento general de visas

State Department

United States. General Accounting Office

1989

U.S.A. immigration guide

Ramon Carrion

1992

Border security

United States. Government Accountability Office.

2004

Treaties, etc

Denmark.

1700

Combating terrorism

United States. Congress. House. Committee on Government Reform. Subcommittee on National Security, Emerging Threats, and International Relations

2004

Tips for U.S. visas

United States. Bureau of Consular Affairs

1993

U.S. immigration & citizenship

Allan Wernick

1997

Foreigners, refugees, or minorities?

Didier Bigo

2012