Kholis, I. “KUALIFIKASI WELDING PROCEDURE SPECIFICATION (WPS) DAN JURU LAS (WELDER) BERDASARKAN ASME SECTION IX DI INDUSTRI MIGAS”. Swara Patra : Majalah Ilmiah PPSDM Migas, vol. 2, no. 3, Dec. 2012, http://ejurnal.ppsdmmigas.esdm.go.id/sp/index.php/swarapatra/article/view/81.