APA (7th ed.) Citation

Petrova E. et al & Petrova E., S. T. (1979). Pre-school education in Bulgaria. Sofia.

Chicago Style (17th ed.) Citation

Petrova E. et al and Sheitanova T. Petrova E. Pre-school Education in Bulgaria. Sofia, 1979.

MLA (8th ed.) Citation

Petrova E. et al and Sheitanova T. Petrova E. Pre-school Education in Bulgaria. Sofia, 1979.

Warning: These citations may not always be 100% accurate.