Não informado. Regulatory Announcement. U.S. Fish and Wildlife Service.
Chicago-viite (17. p.)Não informado. Regulatory Announcement. Washington: U.S. Fish and Wildlife Service.
MLA-viite (8. p.)Não informado. Regulatory Announcement. U.S. Fish and Wildlife Service.
Varoitus: Nämä viitteet eivät aina ole täysin luotettavia.