Perhaps you should try some spelling variations:
theo chieu » theo tieu, theo chu, thi chieu
hanh trinh » canh tranh, hanh chinh
thong cong » trong cong, tong cong, thong thong
dung cong » dung trong
ho chieu » hoc thieu, doi chieu, mot chieu
trinh ve » trinh he, trinh va, trinh vi
dan toan » van toan, dan than, manh toan
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: ((theo chieu) OR (ho chieu)) sach - hanh trinh ve ((thong cong) or (dung cong)) dan toan cao~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((theo chieu) OR (ho chieu)) sach - hanh trinh ve ((thong cong) OR (dung cong)) dan toan cao.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((theo chieu) OR (ho chieu)) sach - hanh trinh ve ((thong cong) or (dung cong)) dan toan cao".
• Adding a wildcard symbol may retrieve word variants: ((theo chieu) OR (ho chieu)) sach - hanh trinh ve ((thong cong) or (dung cong)) dan toan cao*.