Perhaps you should try some spelling variations:
manh trung » manh tung, thanh trung, manh hung
chiet tach » chieu sach
nhung cong » dung cong, thong cong, hang cong
hieu lang » chieu sang, hieu quang, nhieu tang
trung cua » truong cua, trung tuan, trung cap
cua nhung » va nhung
van toan » van tan, van thanh, manh toan
van tuan » van quan, van ban, anh tuan

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: ho ((chiet tach) OR (hieu lang)) - manh trung cua nhung cong ((van toan) OR (van tuan)) cao~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "ho ((chiet tach) or (hieu lang)) - manh trung cua nhung cong ((van toan) OR (van tuan)) cao~".
• Adding a wildcard symbol may retrieve word variants: ho ((chiet tach) or (hieu lang)) - manh trung cua nhung cong ((van toan) OR (van tuan)) cao*.