Perhaps you should try some spelling variations:
thien danh » thien anh, thien dang, thien thanh
chieu sang » chieu sach, chieu xanh, hieu lang
doanh hoan » doanh doanh, doanh khoa, doanh nhan
dong tac » cong tac, dong bac, dong tam
dong tai » dung tai, luong tai, cong tac
hoan va » khoan va, hoang va, doan va

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

• Performing a fuzzy search may retrieve terms with similar spellings: hoc ((thien danh) or (chieu sang)) - doanh hoan va thuong ((dong tac) OR (dong tai)) van ban~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc ((thien danh) OR (chieu sang)) - doanh hoan va thuong ((dong tac) OR (dong tai)) van ban.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc ((thien danh) or (chieu sang)) - doanh hoan va thuong ((dong tac) OR (dong tai)) van ban".
• Adding a wildcard symbol may retrieve word variants: hoc ((thien danh) or (chieu sang)) - doanh hoan va thuong ((dong tac) OR (dong tai)) van ban*.