Cita APA (7th ed.)

Vien, N. K. (1972). Agricultural problems: Some technical aspects. [s.n.].

Cita Chicago (17th ed.)

Vien, Nguyen Khac. Agricultural Problems: Some Technical Aspects. Hanoi: [s.n.], 1972.

Cita MLA (9th ed.)

Vien, Nguyen Khac. Agricultural Problems: Some Technical Aspects. [s.n.], 1972.