RANCANG BANGUN DAN PERBAIKAN MESIN BOR PORTABEL DAN UJI UNJUK KERJA DENGAN BAHAN BESI TUANG ST 40 DAN BESI TUANG ST 60 ( FABRICATION AND REPAIR PORTABLE DRILLING MACHINES AND TEST PERFORMANCE WITH CAST IRON CAST IRON ST 40 AND ST 60 ) - Alex, Dwi Aryanto (2010)