Cita APA (7a ed.)

Penin, R., Traykov, T., Zhelev, D., & Stoyanova, V. (2018). Geography and economics. Klett Bulgaria.

Cita Chicago Style (17a ed.)

Penin, Rumen, Toni Traykov, Dimitar Zhelev, y Valentina Stoyanova. Geography and Economics. Sofija: Klett Bulgaria, 2018.

Cita MLA (9a ed.)

Penin, Rumen, et al. Geography and Economics. Klett Bulgaria, 2018.