Perhaps you should try some spelling variations:
nhung cong » dung cong, thong cong, hang cong
chieu xanh » chieu sach, chieu sang, chieu tinh
hien xanh » hien hanh, hien nhanh, hien khanh
tranh va » tranh van, trang va, trinh va
san toan » van toan, manh toan, xuan toan
dan toan » van toan, dan than, manh toan

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 ((hien xanh) OR (chieu xanh)) - canh tranh va nhung cong ((san toan) OR (dan toan)) cau~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc ((hien xanh) OR (chieu xanh)) - canh tranh va nhung cong ((san toan) or (dan toan)) cau~".
• Adding a wildcard symbol may retrieve word variants: hoc ((hien xanh) OR (chieu xanh)) - canh tranh va nhung cong ((san toan) or (dan toan)) cau*.