Gaya APA

Shiferaw, ., Siregar, C, A. (2005). Natural resources management in agriculture: methods for assessing economic and environmental impacts . Cambridge: CAB International.

Gaya MLA

Shiferaw, ., Siregar, Chairil, Anwar. "Natural resources management in agriculture: methods for assessing economic and environmental impacts". Cambridge: CAB International, 2005. Cetak.