APA
Panjaitan L, . (1990). Cost price analysis of several rubber qualities and their development. A case study at a government-owned estate in North Sumatra. : Bulletin Perkaretan.
Chicago
Panjaitan L, . 1990. Cost price analysis of several rubber qualities and their development. A case study at a government-owned estate in North Sumatra. : Bulletin Perkaretan.
Harvard
Panjaitan L, . (1990). Cost price analysis of several rubber qualities and their development. A case study at a government-owned estate in North Sumatra. : Bulletin Perkaretan.
MLA
Panjaitan L, . Cost price analysis of several rubber qualities and their development. A case study at a government-owned estate in North Sumatra. : Bulletin Perkaretan. 1990.