Perhaps you should try some spelling variations:
thieu sach » thien hach, hieu cach, theo sach
chieu sach » chinh sach, chiet tach, chieu sang
nhung cong » dung cong, thong cong, hang cong
hanh hang » thanh hang, hang hang, hanh han
ca nhung » cua nhung, cam nhung, va nhung
van toan » van tan, van thanh, manh toan
van tuan » van quan, van ban, anh tuan
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 ((thieu sach) or (chieu sach)) - hanh hang ca nhung cong ((van toan) OR (van tuan)) cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc ((thieu sach) OR (chieu sach)) - hanh hang ca nhung cong ((van toan) OR (van tuan)) cau.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc ((thieu sach) or (chieu sach)) - hanh hang ca nhung cong ((van toan) OR (van tuan)) cau".
• Adding a wildcard symbol may retrieve word variants: hoc ((thieu sach) or (chieu sach)) - hanh hang ca nhung cong ((van toan) OR (van tuan)) cau*.