Perhaps you should try some spelling variations:
duong vanh » duong van, duong xanh, duong anh
duong manh » duong van
hieu lang » chieu sang, hieu quang, nhieu tang
canh manh » lanh manh, cach mang, van manh
cua nhung » va nhung
hoc hieu » hoc thieu, hoc hien, doc hieu
toan cau » toan cao, toan ban, toan tap

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 hieu lang - ((canh manh) OR (canh tranh)) cua nhung ((duong vanh) OR (duong manh)) toan cau~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc hieu lang - ((canh manh) OR (canh tranh)) cua nhung ((duong vanh) or (duong manh)) toan cau~".
• Adding a wildcard symbol may retrieve word variants: hoc hieu lang - ((canh manh) OR (canh tranh)) cua nhung ((duong vanh) or (duong manh)) toan cau*.