Perhaps you should try some spelling variations:
cong thanh » dong thanh, cong trinh, cong tan
hieu lang » chieu sang, hieu quang, nhieu tang
va phuong » cac phuong
hoc hieu » hoc thieu, hoc hien, doc hieu
hanh han » hanh nhan, hanh phan, hanh san
toan cao » toan tap
toan ban » van 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 hieu lang - hanh han ((va phuong) or (va thuong)) cong thanh ((toan cao) or (toan ban))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc hieu lang - hanh han ((va phuong) OR (va thuong)) cong thanh ((toan cao) OR (toan ban)).
• Adding a wildcard symbol may retrieve word variants: hoc hieu lang - hanh han ((va phuong) or (va thuong)) cong thanh ((toan cao) or (toan ban))*.