Perhaps you should try some spelling variations:
thiet tach » chiet tach, thien hach, thuat tach
thanh tung » thanh cong
dung chung » dung cong, dung ung, dung trung
hoc thiet » hoc thieu, hoc thuyet, hoc hien
chung han » chung nhan, chung than, chuong han
han than » khan than, phan than, ban than
than cau » toan cau, phan cau, than cap
va dung » van dung, va duong, vat dung

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

• Performing a fuzzy search may retrieve terms with similar spellings: hoc thiet tach - ((thanh trung) or (thanh tung)) va dung chung han than cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc thiet tach - ((thanh trung) OR (thanh tung)) va dung chung han than cau*.