Perhaps you should try some spelling variations:
thanh trung » thanh tung
theo chieu » theo tieu, ho chieu, theo chu
nhung cong » dung cong, thong cong, hang cong
hoc thieu » toc thieu, hoc hien
trung va » truong va, trang va, trung ha
tan toan » tan tran, van toan, dan toan
tap toan » tap doan, tap quan, bai 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 (hoc thieu)) sach - thanh trung va nhung cong ((tan toan) OR (tap toan)) cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((theo chieu) OR (hoc thieu)) sach - thanh trung va nhung cong ((tan toan) OR (tap toan)) cau.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((theo chieu) or (hoc thieu)) sach - thanh trung va nhung cong ((tan toan) OR (tap toan)) cau".
• Adding a wildcard symbol may retrieve word variants: ((theo chieu) or (hoc thieu)) sach - thanh trung va nhung cong ((tan toan) OR (tap toan)) cau*.