Perhaps you should try some spelling variations:
"trinh duong luan van tien thanh" » "trinh dung luan van tien thanh", "trinh phuong luan van tien thanh", "dinh duong luan van tien thanh", "trinh dong luan van tien thanh", "trinh duong quan van tien thanh", "trinh duong luan van tien thinh", "trinh duong luan van tran thanh", "trinh duong luan van den thanh", "trinh duong luan toan tien thanh", "trinh duong luan van tuan thanh"
"tinh quang tran van hieu soat" » "tinh quang tuan van hieu soat", "tinh quang trung van hieu soat", "tinh quang thanh van hieu soat", "tinh quang tran van hieu suat", "tinh quang tran van hieu hoat", "tinh quang tran van hieu luat", "tinh quang tran cao hieu soat", "dinh quang tran van hieu soat", "minh quang tran van hieu soat", "kinh quang tran van hieu soat"

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 tran van hieu soat") or ("trinh duong luan van tien thanh"))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("tinh quang tran van hieu soat") OR ("trinh duong luan van tien thanh")).
• Removing quotes may allow a broader search: (( tinh quang tran van hieu soat ) or ( trinh duong luan van tien thanh )).
• Adding a wildcard symbol may retrieve word variants: (("tinh quang tran van hieu soat") or ("trinh duong luan van tien thanh"))*.