Perhaps you should try some spelling variations:
"tinh quang trung va kiem soat" » "tinh truong trung va kiem soat", "tinh quang trung va kiem toan", "tinh quang truong va kiem soat", "tinh quang trang va kiem soat", "tinh quang trung ha kiem soat", "tinh quang trung van kien soat", "dinh quang trung va kiem soat", "minh quang trung va kiem soat", "kinh quang trung va kiem soat"
"trinh dung lan van hiep hoa" » "trinh dung luan van hiep hoa", "trinh dung land van hiep hoa", "trinh dung lam van hiep hoa", "trinh dung lan van hieu hoa", "trinh dung lan van hien hoa", "trinh dung lan van chien hoa", "trinh dung lan van hien khoa", "trinh dung lan van dien hoa", "trinh dung lang van hiep hoa", "trinh dung tan van hiep hoa"

Try widening your search to All Fields.

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

• Performing a fuzzy search may retrieve terms with similar spellings: (("tinh quang trung va kiem soat") or ("trinh dung lan van hiep hoa"))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("tinh quang trung va kiem soat") OR ("trinh dung lan van hiep hoa")).
• Removing quotes may allow a broader search: (( tinh quang trung va kiem soat ) or ( trinh dung lan van hiep hoa )).
• Adding a wildcard symbol may retrieve word variants: (("tinh quang trung va kiem soat") or ("trinh dung lan van hiep hoa"))*.