Perhaps you should try some spelling variations:
thiet tach » chiet tach, thien hach, thuat tach
thanh tung » thanh cong
nhung cong » dung cong, thong cong, hang cong
cua nhung » va nhung
ho thiet » hoc thiet, hoa thiet, so thiet
tac toan » tam toan, hach toan, tich toan
tap toan » tap doan, tap quan, bai toan

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

• If you are trying to use Boolean operators, they must be ALL CAPS: ho thiet tach - ((thanh trung) OR (thanh tung)) cua nhung cong ((tac toan) OR (tap toan)) ban~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "ho thiet tach - ((thanh trung) or (thanh tung)) cua nhung cong ((tac toan) OR (tap toan)) ban~".
• Adding a wildcard symbol may retrieve word variants: ho thiet tach - ((thanh trung) or (thanh tung)) cua nhung cong ((tac toan) OR (tap toan)) ban*.