Abdul Karim, N. A., and A. F. Wahab. “Data Grid Kabur Dalam Sistem Maklumat Geografi (GIS): Fuzzy Data Grid in Geographic Information System (GIS)”. Journal of Science and Mathematics Letters, vol. 5, no. 1, Dec. 2013, pp. 8-18, https://ejournal.upsi.edu.my/index.php/JSML/article/view/341.