Cita APA (7a ed.)

Helmus, T. M., & Arnsdorf, V. E. (1984). The United States and its neighbors. Silver Burdett.

Cita Chicago Style (17a ed.)

Helmus, Timothy M., y Val E. Arnsdorf. The United States and Its Neighbors. Morristown, NJ [u.a.]: Silver Burdett, 1984.

Cita MLA (9a ed.)

Helmus, Timothy M., y Val E. Arnsdorf. The United States and Its Neighbors. Silver Burdett, 1984.