Perhaps you should try some spelling variations:
nhanh chong » thanh cong, khanh phong
chong phap » phuong phap
hieu lang » chieu sang, hieu quang, nhieu tang
long cong » luong cong, cong cong, tong cong
dung cong » dung trong
doi hieu » doi chieu, doc hieu, doi hien
tan van » tran van, tang van, luan van

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: doi hieu lang - nhanh chong phap ((long cong) OR (dung cong)) tan van ban~.
• Adding a wildcard symbol may retrieve word variants: doi hieu lang - nhanh chong phap ((long cong) or (dung cong)) tan van ban*.