Perhaps you should try some spelling variations:
duong tinh » duong minh, duong sinh, dong tinh
dong duong » tuong duong, cuong duong, dong thong
hieu lang » chieu sang, hieu quang, nhieu tang
nhu hieu » nhu hien, nha hieu, nho hieu
dung cua » dung luan
toan cau » toan cao, toan tap, toan tai
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: nhu hieu lang - hanh ((dung cua) OR (dung cho)) dong duong tinh ((toan cau) or (toan ban))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: nhu hieu lang - hanh ((dung cua) OR (dung cho)) dong duong tinh ((toan cau) OR (toan ban)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "nhu hieu lang - hanh ((dung cua) OR (dung cho)) dong duong tinh ((toan cau) or (toan ban))".
• Adding a wildcard symbol may retrieve word variants: nhu hieu lang - hanh ((dung cua) OR (dung cho)) dong duong tinh ((toan cau) or (toan ban))*.