APA (7th ed.) Citation

Todorov, N., Melnishki, L., & Dinev, L. (1968). Bulgaria; historical and geographical outline. Sofia P..

Chicago Style (17th ed.) Citation

Todorov, Nikolaĭ, Li͡uben Melnishki, and Li︠u︡bomir Dinev. Bulgaria; Historical and Geographical Outline. [Sofia]: Sofia P., 1968.

MLA (9th ed.) Citation

Todorov, Nikolaĭ, et al. Bulgaria; Historical and Geographical Outline. Sofia P., 1968.