Perhaps you should try some spelling variations:
thiet tach » chiet tach, thien hach, thuat tach
thanh tung » thanh cong
hoc thiet » hoc thieu, hoc thuyet, hoc hien
cap phan » cac phan, cao phan, cau phan
cong tan » cong san, cong thanh, cong ty
cong tac » cong ty
phan cau » phan dau, phan cac, phan tu
cap han » cap can, cap hay, cap van

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 tung ((cap han) or (cap phan)) ((cong tan) OR (cong tac)) phan cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc thiet tach - thanh tung ((cap han) OR (cap phan)) ((cong tan) OR (cong tac)) phan cau.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc thiet tach - thanh tung ((cap han) or (cap phan)) ((cong tan) OR (cong tac)) phan cau".
• Adding a wildcard symbol may retrieve word variants: hoc thiet tach - thanh tung ((cap han) or (cap phan)) ((cong tan) OR (cong tac)) phan cau*.