Cita APA (7th ed.)

Birnbaum, S., & Birnbaum, A. M. (1990). Birnbaum's Europe 1991. Houghton Mifflin.

Cita Chicago (17th ed.)

Birnbaum, Stephen, i Alexandra Mayes Birnbaum. Birnbaum's Europe 1991. Boston: Houghton Mifflin, 1990.

Cita MLA (9th ed.)

Birnbaum, Stephen, i Alexandra Mayes Birnbaum. Birnbaum's Europe 1991. Houghton Mifflin, 1990.