Perhaps you should try some spelling variations:
hanh trinh » canh tranh, hanh chinh
chieu sang » chieu sach, chieu xanh, nhieu tang
hieu lang » hieu quang, nhieu tang, hieu van
trinh han » trinh quan
dung cong » dung trong
hang cong » dang cong, hang nong, bang cong
tap toan » tap doan, tap quan, bai 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: ho ((chieu sang) OR (hieu lang)) - hanh trinh han ((dung cong) or (hang cong)) tap toan ban~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ho ((chieu sang) OR (hieu lang)) - hanh trinh han ((dung cong) OR (hang cong)) tap toan ban.
• The words AND, OR and NOT may confuse the search; try adding quotes: "ho ((chieu sang) OR (hieu lang)) - hanh trinh han ((dung cong) or (hang cong)) tap toan ban".
• Adding a wildcard symbol may retrieve word variants: ho ((chieu sang) OR (hieu lang)) - hanh trinh han ((dung cong) or (hang cong)) tap toan ban*.