Perhaps you should try some spelling variations:
chieu sach » chinh sach, chiet tach, chieu sang
hanh trang » thanh trung, hanh trinh, minh trang
nhung cung » nhung dung, nhung cang, nhung vung
nhung cong » dung cong, thong cong, hang cong
ho chieu » theo chieu, hoc thieu, doi chieu
bai toan » bai tap
toan cau » toan cao, toan ban, toan tap

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

• Performing a fuzzy search may retrieve terms with similar spellings: ho chieu sach - ((hanh trang) or (canh tranh)) va ((nhung cung) OR (nhung cong)) bai toan cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ho chieu sach - ((hanh trang) OR (canh tranh)) va ((nhung cung) OR (nhung cong)) bai toan cau.
• The words AND, OR and NOT may confuse the search; try adding quotes: "ho chieu sach - ((hanh trang) or (canh tranh)) va ((nhung cung) OR (nhung cong)) bai toan cau".
• Adding a wildcard symbol may retrieve word variants: ho chieu sach - ((hanh trang) or (canh tranh)) va ((nhung cung) OR (nhung cong)) bai toan cau*.