Perhaps you should try some spelling variations:
thanh trung » thanh tung
hieu quang » thieu quang, hieu quan, hieu qua
trung tuan » trung thanh, trung tam, tran tuan
thong cong » trong cong, tong cong, thong thong
hieu lang » chieu sang, nhieu tang, hieu van
dung cong » dung trong
van thanh » ban thanh, van tuan
thanh tay » thanh tai, thanh toan, thanh thuy

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

• Performing a fuzzy search may retrieve terms with similar spellings: doi ((hieu lang) OR (hieu quang)) - thanh trung tuan ((dung cong) or (thong cong)) van thanh tay~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doi ((hieu lang) OR (hieu quang)) - thanh trung tuan ((dung cong) OR (thong cong)) van thanh tay.
• The words AND, OR and NOT may confuse the search; try adding quotes: "doi ((hieu lang) OR (hieu quang)) - thanh trung tuan ((dung cong) or (thong cong)) van thanh tay".
• Adding a wildcard symbol may retrieve word variants: doi ((hieu lang) OR (hieu quang)) - thanh trung tuan ((dung cong) or (thong cong)) van thanh tay*.