APA
Syamsu Y, . (1991). Second evaluation of smallholder rubber after the implementation of SIR scheme 1988 in north Sumatra. : Bulletin Perkaretan.
Chicago
Syamsu Y, . 1991. Second evaluation of smallholder rubber after the implementation of SIR scheme 1988 in north Sumatra. : Bulletin Perkaretan.
Harvard
Syamsu Y, . (1991). Second evaluation of smallholder rubber after the implementation of SIR scheme 1988 in north Sumatra. : Bulletin Perkaretan.
MLA
Syamsu Y, . Second evaluation of smallholder rubber after the implementation of SIR scheme 1988 in north Sumatra. : Bulletin Perkaretan. 1991.