Perhaps you should try some spelling variations:
chieu sach » chinh sach, chiet tach, chieu sang
duong manh » duong van
hieu cach » hieu cac, hieu ca, biet cach
manh toan » thanh toan, anh tuan, tinh toan
cua dung » cua dang, cua dong, cua rung
qua dung » quang dung, su dung, qua song
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: hoc ((hieu cach) OR (chieu sach)) - canh tranh ((cua dung) or (qua dung)) duong manh toan cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc ((hieu cach) OR (chieu sach)) - canh tranh ((cua dung) OR (qua dung)) duong manh toan cau.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc ((hieu cach) OR (chieu sach)) - canh tranh ((cua dung) or (qua dung)) duong manh toan cau".
• Adding a wildcard symbol may retrieve word variants: hoc ((hieu cach) OR (chieu sach)) - canh tranh ((cua dung) or (qua dung)) duong manh toan cau*.