Perhaps you should try some spelling variations:
hieu quang » thieu quang, hieu quan, hieu qua
hieu lang » chieu sang, nhieu tang, hieu van
chinh cua » chinh sua, hinh cua, chinh luan
dung cong » dung trong
chinh ca » chinh ta, chinh va, chinh tai
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: ho ((hieu lang) OR (hieu quang)) - hanh ((chinh cua) or (chinh ca)) dung cong dan toan cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ho ((hieu lang) OR (hieu quang)) - hanh ((chinh cua) OR (chinh ca)) dung cong dan toan cau.
• The words AND, OR and NOT may confuse the search; try adding quotes: "ho ((hieu lang) OR (hieu quang)) - hanh ((chinh cua) or (chinh ca)) dung cong dan toan cau".
• Adding a wildcard symbol may retrieve word variants: ho ((hieu lang) OR (hieu quang)) - hanh ((chinh cua) or (chinh ca)) dung cong dan toan cau*.