Perhaps you should try some spelling variations:
chieu sach » chinh sach, chiet tach, chieu xanh
chieu sang » chieu xanh, hieu lang, nhieu tang
hanh trung » thanh trung, hanh trang, manh trung
tuan trong » thuan trong, tran trong, toan trong
quan trong » gian trong
cong hach » cong sach, cong thanh, cong khanh
hach toan » thanh toan, manh toan
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 ((chieu sach) OR (chieu sang)) - hanh trung ((tuan trong) or (quan trong)) cong hach toan cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc ((chieu sach) OR (chieu sang)) - hanh trung ((tuan trong) OR (quan trong)) cong hach toan cau.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc ((chieu sach) OR (chieu sang)) - hanh trung ((tuan trong) or (quan trong)) cong hach toan cau".
• Adding a wildcard symbol may retrieve word variants: hoc ((chieu sach) OR (chieu sang)) - hanh trung ((tuan trong) or (quan trong)) cong hach toan cau*.