Perhaps you should try some spelling variations:
hieu quang » thieu quang, hieu quan, hieu qua
hanh trang » thanh trung, canh tranh, hanh trinh
thong cong » trong cong, tong cong, phong chong
hieu lang » chieu sang, nhieu tang, hieu van
trang cua » tranh cua, tang cua, trung cua
vang toan » van toan, dang toan, quang toan
toan ban » van ban

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

• Performing a fuzzy search may retrieve terms with similar spellings: hoc ((hieu lang) or (hieu quang)) - hanh trang cua ((thong cong) OR (thong thong)) vang toan ban~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc ((hieu lang) OR (hieu quang)) - hanh trang cua ((thong cong) OR (thong thong)) vang toan ban.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc ((hieu lang) or (hieu quang)) - hanh trang cua ((thong cong) OR (thong thong)) vang toan ban".
• Adding a wildcard symbol may retrieve word variants: hoc ((hieu lang) or (hieu quang)) - hanh trang cua ((thong cong) OR (thong thong)) vang toan ban*.