Perhaps you should try some spelling variations:
chieu xanh » chieu sach, chieu tinh, hieu manh
chieu sang » chieu sach, hieu lang, nhieu tang
doanh hoan » doanh doanh, doanh khoa, doanh nhan
thong cong » tong cong, thong thong, phong chong
tac hang » tac vang, bac thang, tac chong
hang ban » hang luan, hang va, hang tai
hoan va » khoan va, hoang va, doan va

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

• If you are trying to use Boolean operators, they must be ALL CAPS: hoc ((chieu xanh) OR (chieu sang)) - doanh hoan va ((thong cong) OR (trong cong)) tac hang ban~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc ((chieu xanh) or (chieu sang)) - doanh hoan va ((thong cong) OR (trong cong)) tac hang ban~".
• Adding a wildcard symbol may retrieve word variants: hoc ((chieu xanh) or (chieu sang)) - doanh hoan va ((thong cong) OR (trong cong)) tac hang ban*.