Perhaps you should try some spelling variations:
theo chieu » theo tieu, ho chieu, theo chu
chieu sach » chinh sach, chiet tach, chieu sang
nhanh lang » nhanh thang, nhan dang, nhanh dong
nhung cong » dung cong, thong cong, hang cong
cua nhung » va nhung
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: theo chieu sach - ((nhanh lang) OR (nhanh quang)) cua nhung cong ((tap toan) OR (tap doan)) tap~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "theo chieu sach - ((nhanh lang) or (nhanh quang)) cua nhung cong ((tap toan) OR (tap doan)) tap~".
• Adding a wildcard symbol may retrieve word variants: theo chieu sach - ((nhanh lang) or (nhanh quang)) cua nhung cong ((tap toan) OR (tap doan)) tap*.