INDIKATOR SOSIAL – EKONOMI UNTUK PENGUKURAN KINERJA LINGKUNGAN KAWASAN INDUSTRI BERBASIS KELAPA SAWIT KEK SEI MANGKEI (IDENTIFICATION OF SOCIAL – ECONOMIC INDICATORS FOR ENVIRONMENTAL PERFORMANCE MEASUREMENT INDUSTRIAL AREAS BASED ON PALM OIL) - fajarwati, indah (Badan Penelitian dan Pengembangan Provinsi Sumatera Utara, 2018)