Perhaps you should try some spelling variations:
"trinh dung luan van thien hoat" » "trinh dung luan van trien hoat", "trinh dung luan van thien thuat", "trinh dung luan van tien hoa", "trinh dung luan van tien hoat", "trinh dung luan van hien hoat", "trinh dung luan van chien hoat", "trinh dung quan van thien hoat", "trinh dung lan van thien hoat"
"tinh quang dam van kiem soat" » "tinh quang nam van kiem soat", "tinh quang lam van kiem soat", "tinh quang dai van kiem soat", "tinh quang dam van kiem toan", "tinh quang dam va kiem soat", "tinh quang dam van kien soat", "tinh quang dam van hieu soat", "tinh quang dao van kiem soat", "tinh quang pham van kiem soat", "dinh quang dam van kiem soat", "minh quang dam van kiem soat", "kinh quang dam van kiem 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 dam van kiem soat") or ("trinh dung luan van thien hoat"))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("tinh quang dam van kiem soat") OR ("trinh dung luan van thien hoat")).
• Removing quotes may allow a broader search: (( tinh quang dam van kiem soat ) or ( trinh dung luan van thien hoat )).
• Adding a wildcard symbol may retrieve word variants: (("tinh quang dam van kiem soat") or ("trinh dung luan van thien hoat"))*.