Perhaps you should try some spelling variations:
nhung cong » dung cong, thong cong, hang cong
hieu lang » chieu sang, hieu quang, nhieu tang
hanh sinh » hanh tinh, hanh dinh, hanh chinh
hinh sinh » tinh sinh, hinh dinh, hinh kinh
bang cong » dang cong, bang song, hang cong
phong cau » thong cau, phong cac, phong cai
doc hieu » toc thieu, hoc thieu, hoc hien

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: doc hieu lang - ((hanh sinh) OR (hinh sinh)) cua ((nhung cong) OR (bang cong)) hai phong cau~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "doc hieu lang - ((hanh sinh) OR (hinh sinh)) cua ((nhung cong) or (bang cong)) hai phong cau~".
• Adding a wildcard symbol may retrieve word variants: doc hieu lang - ((hanh sinh) OR (hinh sinh)) cua ((nhung cong) or (bang cong)) hai phong cau*.