Perhaps you should try some spelling variations:
chiet tach » chieu sach
hanh trinh » canh tranh, hanh chinh
hieu lang » chieu sang, hieu quang, nhieu tang
dung cong » dung trong
van thanh » ban thanh, van tuan
trinh va » trinh van, trinh vat, trinh ve
van toan » van tuan, van tan, manh toan
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: theo ((chiet tach) or (hieu lang)) - hanh trinh va dung cong ((van toan) or (van thanh)) cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: theo ((chiet tach) OR (hieu lang)) - hanh trinh va dung cong ((van toan) OR (van thanh)) cau.
• Adding a wildcard symbol may retrieve word variants: theo ((chiet tach) or (hieu lang)) - hanh trinh va dung cong ((van toan) or (van thanh)) cau*.