Perhaps you should try some spelling variations:
thieu sang » thieu khang, thieu quang, hieu lang
chieu sang » chieu sach, chieu xanh, hieu lang
canh trinh » hanh trinh, canh tinh, anh trinh
dong doanh » dung doanh, trong doanh, doanh doanh
dong dong » dong duong, cong dong, dung dong
doanh van » doan van, doanh va, doanh 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 ((thieu sang) OR (chieu sang)) - ((canh trinh) or (canh tranh)) van dong dong doanh van ban~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc ((thieu sang) OR (chieu sang)) - ((canh trinh) OR (canh tranh)) van dong dong doanh van ban.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc ((thieu sang) OR (chieu sang)) - ((canh trinh) or (canh tranh)) van dong dong doanh van ban".
• Adding a wildcard symbol may retrieve word variants: hoc ((thieu sang) OR (chieu sang)) - ((canh trinh) or (canh tranh)) van dong dong doanh van ban*.