Perhaps you should try some spelling variations:
hien quang » dien quang, bien quang, hien quan
canh trinh » canh tranh, hanh trinh, canh tinh
nhung cong » thong cong, hang cong, nhung don
dung cong » dung trong
trinh va » trinh van, trinh vat, trinh ve
toan cao » toan ban
toan tap » toan ban

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

• Performing a fuzzy search may retrieve terms with similar spellings: hoc hien quang - canh trinh va ((nhung cong) or (dung cong)) san ((toan cao) or (toan tap))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc hien quang - canh trinh va ((nhung cong) OR (dung cong)) san ((toan cao) OR (toan tap)).
• Adding a wildcard symbol may retrieve word variants: hoc hien quang - canh trinh va ((nhung cong) or (dung cong)) san ((toan cao) or (toan tap))*.