Perhaps you should try some spelling variations:
thanh thuong » thanh huong, thanh chuong, thanh phuong
thuong thanh » truong thanh, phuong thanh, thong thanh
dung thuong » hang thuong, cong thuong, dung thuoc
hieu sang » chieu sang, hieu quang, nhieu tang
hieu lang » chieu sang, hieu quang, nhieu tang
dan chan » dan gian, dan ca, van chat
chan cau » phan cau, can cau, chinh cau

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) OR (hieu lang)) - thanh thuong thanh ((dung trong) or (dung thuong)) dan chan cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc ((hieu sang) OR (hieu lang)) - thanh thuong thanh ((dung trong) OR (dung thuong)) dan chan cau.
• The words AND, OR and NOT may confuse the search; try adding quotes: "doc ((hieu sang) OR (hieu lang)) - thanh thuong thanh ((dung trong) or (dung thuong)) dan chan cau".
• Adding a wildcard symbol may retrieve word variants: doc ((hieu sang) OR (hieu lang)) - thanh thuong thanh ((dung trong) or (dung thuong)) dan chan cau*.