Perhaps you should try some spelling variations:
hieu quang » thieu quang, hieu quan, hieu qua
hanh trinh » canh tranh, hanh chinh
hieu lang » chieu sang, nhieu tang, hieu van
trinh va » trinh van, trinh vat, trinh ve
cong dan » cong tan, huong dan, cong dong
cong san » cong tac
chan cau » phan cau, can cau, chinh cau

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

• Performing a fuzzy search may retrieve terms with similar spellings: doc ((hieu lang) or (hieu quang)) - hanh trinh va nhung ((cong dan) or (cong san)) chan cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc ((hieu lang) OR (hieu quang)) - hanh trinh va nhung ((cong dan) OR (cong san)) chan cau.
• Adding a wildcard symbol may retrieve word variants: doc ((hieu lang) or (hieu quang)) - hanh trinh va nhung ((cong dan) or (cong san)) chan cau*.