Perhaps you should try some spelling variations:
thanh tuong » thanh thuong, thanh tung, thanh huong
hieu sang » chieu sang, hieu lang, hieu quang
tuong cua » truong cua, huong cua, thong cua
cong cong » cong dong, trong cong, dang cong
dung cong » dung trong
doc hieu » toc thieu, hoc thieu, hoc hien
toan ban » van ban
toan cao » toan tap

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 sang - thanh tuong cua ((cong cong) OR (dung cong)) dan ((toan ban) OR (toan cao))~.
• Adding a wildcard symbol may retrieve word variants: doc hieu sang - thanh tuong cua ((cong cong) or (dung cong)) dan ((toan ban) or (toan cao))*.