“PREDICTING THE VARIABILITY OF COPPER AND ZINC IN LEAF AND SOIL OF OIL PALM PLANTED ON A 12 HA LAND USING GEOSPATIAL INFORMATION SYSTEM TECHNOLOGY”.
Jurnal Teknologi (Sciences & Engineering), vol. 77, no. 24, Dec. 2015,
https://doi.org/10.11113/jt.v77.6717.