http://www.loc.gov/mods/v3 http://www.loc.gov/standards/mods/v3/mods-3-2.xsd
Thời điểm giao kết hợp đồng trong pháp luật của một số nước trên thế giới, các bộ nguyên tắc hợp đồng quốc tế và kinh nghiệm cho Việt Nam