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 cua » tinh cua, trinh luat, trinh quan
dong cong » duong cong, dung cong, dang cong
cua dong » chua dong, cua cong, cua dang
bai toan » bai 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 trinh cua dong cong ((bai toan) or (tan tran)) cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ho ((hieu lang) OR (hieu quang)) - hanh trinh cua dong cong ((bai toan) OR (tan tran)) cau.
• The words AND, OR and NOT may confuse the search; try adding quotes: "ho ((hieu lang) OR (hieu quang)) - hanh trinh cua dong cong ((bai toan) or (tan tran)) cau".
• Adding a wildcard symbol may retrieve word variants: ho ((hieu lang) OR (hieu quang)) - hanh trinh cua dong cong ((bai toan) or (tan tran)) cau*.