Perhaps you should try some spelling variations:
duong trong » dung trong
chieu sach » chinh sach, chiet tach, chieu sang
hieu lang » chieu sang, hieu quang, nhieu tang
quang van » quang ban, quan van, quang uan
van duong » van dong, van dung, van phong
trong dan » trong dang, trong san, trong tan
dan than » dan chan, ban than, van than
than man » than ma, thanh san, tran manh

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