Perhaps you should try some spelling variations:
thanh tung » thanh cong
theo lieu » theo tieu, theo chieu, theo yeu
lieu tinh » trieu tinh, diep tinh, bien tinh
dang cong » dung cong
tan toan » tan tran, tap toan, van toan
bai toan » bai tap
tung va » trung va, tuong va, dung va
va dang » van dang, va nang, va lang

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

• Performing a fuzzy search may retrieve terms with similar spellings: theo lieu tinh - thanh tung va dang cong ((tan toan) or (bai toan)) tap~.
• If you are trying to use Boolean operators, they must be ALL CAPS: theo lieu tinh - thanh tung va dang cong ((tan toan) OR (bai toan)) tap.
• Adding a wildcard symbol may retrieve word variants: theo lieu tinh - thanh tung va dang cong ((tan toan) or (bai toan)) tap*.