Perhaps you should try some spelling variations:
chieu sach » chinh sach, chiet tach, chieu sang
trinh quan » tinh quang, trinh luat, trinh han
nhung cong » dung cong, thong cong, hang cong
trinh cua » tinh cua, trinh luat, trinh luan
ho chieu » theo chieu, hoc thieu, doi chieu
tan toan » tan tran, van toan, dan toan
tap toan » tap doan, tap quan, bai toan

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: ho chieu sach - hanh ((trinh cua) OR (trinh quan)) nhung cong ((tan toan) OR (tap toan)) cau~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "ho chieu sach - hanh ((trinh cua) or (trinh quan)) nhung cong ((tan toan) OR (tap toan)) cau~".
• Adding a wildcard symbol may retrieve word variants: ho chieu sach - hanh ((trinh cua) or (trinh quan)) nhung cong ((tan toan) OR (tap toan)) cau*.