Perhaps you should try some spelling variations:
theo chieu » theo tieu, ho chieu, theo chu
cong trong » cong thuong, duong trong, cong trinh
hanh hang » thanh hang, hang hang, hanh han
theo yeu » theo tieu, thiet yeu, theo chu
cua toan » cuu toan, xuan toan, cua thanh
hang ca » hang va, nang cao, hang tai
ca cong » cua cong, cac cong, cao cong
ca toan » va toan, bai toan, tap toan

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

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