Perhaps you should try some spelling variations:
chieu sach » chinh sach, chiet tach, chieu sang
duong cong » dung cong, luong cong, duong trong
hieu lang » chieu sang, hieu quang, nhieu tang
trinh va » trinh van, trinh vat, trinh vi
trinh ve » trinh he, trinh vi, trinh viet
cong dan » cong san, cong tan, huong dan
dan toan » van toan, dan than, manh toan
toan cau » toan cao, toan ban, toan tap

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

• Performing a fuzzy search may retrieve terms with similar spellings: doi ((chieu sach) or (hieu lang)) - hanh ((trinh va) OR (trinh ve)) duong cong dan toan cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doi ((chieu sach) OR (hieu lang)) - hanh ((trinh va) OR (trinh ve)) duong cong dan toan cau.
• The words AND, OR and NOT may confuse the search; try adding quotes: "doi ((chieu sach) or (hieu lang)) - hanh ((trinh va) OR (trinh ve)) duong cong dan toan cau".
• Adding a wildcard symbol may retrieve word variants: doi ((chieu sach) or (hieu lang)) - hanh ((trinh va) OR (trinh ve)) duong cong dan toan cau*.