Perluasan keanggotaan Uni Eropa berdasarkan traktat maastricht 1992 dan kriteria copenhagen 1993 dalam proses penerimaan Turki di Uni Eropa = The European union enlargement according to maastricht treaty 1992 and copenhagen criteria 1993 on the enlargement process of Turkey into the European union - Sihombing, Mangaratua, author (2014)