Perhaps you should try some spelling variations:
thiet tach » thien hach, thuat tach
chiet tach » chieu sach
hanh trang » thanh trung, canh tranh, hanh trinh
dung cong » dung trong
trang va » tran van, hang va
cong tan » cong tac, cong san, cong thanh
than cau » toan cau, than cap, thanh chau
phan cau » phan dau, phan cac, phan tu
va dung » van dung, va duong, vat dung

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: hoc ((thiet tach) OR (chiet tach)) - hanh trang va dung cong tan ((than cau) OR (phan cau))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc ((thiet tach) OR (chiet tach)) - hanh trang va dung cong tan ((than cau) or (phan cau))~".
• Adding a wildcard symbol may retrieve word variants: hoc ((thiet tach) OR (chiet tach)) - hanh trang va dung cong tan ((than cau) or (phan cau))*.