Perhaps you should try some spelling variations:
"tinh dung luan van thien hoat" » "tinh dung luan van trien hoat", "tinh dung luan van thien thuat", "tinh dung luan van tien hoa", "tin dung luan van thien hoat", "tinh quang luan van thien hoat", "tinh huong luan van thien hoat", "tinh dung luan van tien hoat", "tinh dung luan van hien hoat", "tinh dung luan van chien hoat", "tinh dung quan van thien hoat", "tinh dung lan van thien hoat"
"trinh dung lam van hieu luat" » "trinh dung lam van hieu qua", "trinh dung tai van hieu luat", "trinh dung dat van hieu luat", "trinh dung ha van hieu luat", "trinh dung lam cao hieu luat", "trinh dung lam san hieu luat", "trinh dung nam van hieu luat", "trinh dung dam van hieu luat"

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

• Performing a fuzzy search may retrieve terms with similar spellings: (("trinh dung lam van hieu luat") or ("tinh dung luan van thien hoat"))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("trinh dung lam van hieu luat") OR ("tinh dung luan van thien hoat")).
• Removing quotes may allow a broader search: (( trinh dung lam van hieu luat ) or ( tinh dung luan van thien hoat )).
• Adding a wildcard symbol may retrieve word variants: (("trinh dung lam van hieu luat") or ("tinh dung luan van thien hoat"))*.