APA

Петков В. Г., . (1986). Jugendbrigaden in Bulgarien. Sofia: Sofia-Press.

Chicago

Петков Валентин Георгиев, . 1986. Jugendbrigaden in Bulgarien. Sofia: Sofia-Press.

Harvard

Петков В. Г., . (1986). Jugendbrigaden in Bulgarien. Sofia: Sofia-Press.

MLA

Петков Валентин Георгиев, . Jugendbrigaden in Bulgarien. Sofia: Sofia-Press. 1986.