Perhaps you should try some spelling variations:
chieu sach » chinh sach, chiet tach, chieu sang
tran nhung » tranh nhung, tran hung, tren nhung
nhung cong » dung cong, thong cong, hang cong
doi chieu » doc hieu, doi chi, mot chieu
anh quang » anh xquang, anh quan, tinh quang
tap toan » tap quan, bai toan
tap doan » tap quan

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

• If you are trying to use Boolean operators, they must be ALL CAPS: doi chieu sach - ((anh quang) OR (nhanh quang)) tran nhung cong ((tap toan) OR (tap doan)) cau~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "doi chieu sach - ((anh quang) OR (nhanh quang)) tran nhung cong ((tap toan) or (tap doan)) cau~".
• Adding a wildcard symbol may retrieve word variants: doi chieu sach - ((anh quang) OR (nhanh quang)) tran nhung cong ((tap toan) or (tap doan)) cau*.