Perhaps you should try some spelling variations:
hien xanh » hien hanh, hien nhanh, chieu xanh
hanh hang » thanh hang, hang hang, hanh mang
hanh han » hanh nhan, hanh phan, hanh san
cong van » cong vang, song van, cong tan
cong san » cong tac
quan cau » quang cao, toan cau, quan ha
va dung » van dung, va duong, vat dung

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 - ((hanh hang) OR (hanh han)) va dung ((cong van) OR (cong san)) quan cau~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc hien xanh - ((hanh hang) or (hanh han)) va dung ((cong van) OR (cong san)) quan cau~".
• Adding a wildcard symbol may retrieve word variants: hoc hien xanh - ((hanh hang) or (hanh han)) va dung ((cong van) OR (cong san)) quan cau*.