Perhaps you should try some spelling variations:
"danh thuc trung quoc viet nam" » "danh thuc trang quoc viet nam", "danh thuc trong quoc viet nam", "danh hoc trung quoc viet nam", "dan thuc trung quoc viet nam", "anh thuc trung quoc viet nam", "dinh thuc trung quoc viet nam", "danh thuc trung nuoc viet nam", "danh thuc trung ngoc viet nam", "danh thuc trung toc viet nam"
"dan bac dong hoc viet nam" » "dan bat dong hoc viet nam", "dan tac dong hoc viet nam", "dan bac tong hoc viet nam", "dan bac dong co viet nam", "dan bac dong luc viet nam", "dan bac dong hoc hien nam", "dan ba dong hoc viet nam", "van bac dong hoc viet nam", "dong bac dong hoc viet nam"

You may be able to get more results by adjusting your search query.

• If you are trying to use Boolean operators, they must be ALL CAPS: (("danh thuc trung quoc viet nam") OR ("dan bac dong hoc viet nam"))~.
• Removing quotes may allow a broader search: (( danh thuc trung quoc viet nam ) or ( dan bac dong hoc viet nam ))~.
• Adding a wildcard symbol may retrieve word variants: (("danh thuc trung quoc viet nam") or ("dan bac dong hoc viet nam"))*.