Perhaps you should try some spelling variations:
chieu sach » chinh sach, chiet tach, chieu sang
cong trong » cong thuong, duong trong, cong trinh
hieu lang » chieu sang, hieu quang, nhieu tang
tinh quan » tinh quang, trinh quan, tin quan
trong dan » trong dang, trong san, trong tan
quan lua » quan luan, quan cua, quang cua
lua cong » luat cong, luan cong, cua cong
dan than » dan chan, ban than, van than
than ban » thanh ban, toan ban, than man

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