Perhaps you should try some spelling variations:
quang thanh » quan thanh, hoang thanh, muong thanh
chieu sach » chinh sach, chiet tach, chieu sang
cong trong » cong thuong, duong trong, cong trinh
hieu lang » chieu sang, hieu quang, nhieu tang
trong tan » trong quan, trong cac, trong ca
tran van » luan van

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 lang) or (chieu sach)) - tinh quang thanh cong trong tan tran van~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc ((hieu lang) OR (chieu sach)) - tinh quang thanh cong trong tan tran van.
• Adding a wildcard symbol may retrieve word variants: doc ((hieu lang) or (chieu sach)) - tinh quang thanh cong trong tan tran van*.