Perhaps you should try some spelling variations:
thanh tung » thanh cong
hieu lang » chieu sang, hieu quang, nhieu tang
tac toan » tam toan, hach toan, tich toan
tap toan » tap doan, tap quan, bai toan
ho hieu » ho chieu, hoi hieu, nho hieu
tung va » trung va, tuong va, dung va
va han » va phan, van han, va hanh

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

• Performing a fuzzy search may retrieve terms with similar spellings: ho hieu lang - thanh tung va han tong ((tac toan) or (tap toan)) tap~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ho hieu lang - thanh tung va han tong ((tac toan) OR (tap toan)) tap.
• Adding a wildcard symbol may retrieve word variants: ho hieu lang - thanh tung va han tong ((tac toan) or (tap toan)) tap*.