Perhaps you should try some spelling variations:
nhanh dong » hanh dong, nhanh chong, anh dong
dong thuan » don thuan, dong chuan, dong thuong
hieu lang » chieu sang, hieu quang, nhieu tang
long cong » luong cong, cong cong, tong cong
dung cong » dung trong
doc hieu » toc thieu, hoc thieu, hoc hien
tan toan » tan tran, tap toan, van toan
toan ban » van ban

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 - nhanh dong thuan ((long cong) OR (dung cong)) tan toan ban~.
• Adding a wildcard symbol may retrieve word variants: doc hieu lang - nhanh dong thuan ((long cong) or (dung cong)) tan toan ban*.