Perhaps you should try some spelling variations:
chieu sach » chinh sach, chiet tach, chieu sang
hieu cach » hieu cac, hieu ca, biet cach
hanh hang » thanh hang, hang hang, hanh han
ca nhung » cua nhung, cam nhung, va nhung
cong van » cong vang, song van, cong tan
cong san » cong tac
toan cau » toan cao, toan ban, toan tap
hang ca » hang va, nang cao, hang tai

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

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