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

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: doc hieu sang - thanh tuong cua ((thong cong) or (dung cong)) dan ((toan cao) or (van ban))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc hieu sang - thanh tuong cua ((thong cong) OR (dung cong)) dan ((toan cao) OR (van ban)).
• Adding a wildcard symbol may retrieve word variants: doc hieu sang - thanh tuong cua ((thong cong) or (dung cong)) dan ((toan cao) or (van ban))*.