Perhaps you should try some spelling variations:
hieu quang » thieu quang, hieu quan, hieu qua
thang nong » thang long, hang nong, tang nong
hieu lang » chieu sang, nhieu tang, hieu van
doanh cua » doanh luan
cua thang » cua hang, cua thanh, xua thang
nong dan » cong dan, nong san, nguong dan
than man » thanh san, tran manh, than phan
than ma » than va, khan ma, nhan ma

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) OR (hieu quang)) - toan doanh cua thang nong dan ((than man) OR (than ma))~.
• Adding a wildcard symbol may retrieve word variants: hoc ((hieu lang) or (hieu quang)) - toan doanh cua thang nong dan ((than man) or (than ma))*.