Perhaps you should try some spelling variations:
chiet tach » chieu sach
hanh trinh » canh tranh, hanh chinh
dung huong » dung thuong, dung phuong, dong huong
hien tach » thien hach, vien bach, hien hanh
trinh va » trinh van, trinh vat, trinh ve
dan toan » van toan, manh toan, xuan toan
dan than » dan chan, ban than, van than
va dung » van dung, va duong, vat dung

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

• Performing a fuzzy search may retrieve terms with similar spellings: hoc ((hien tach) or (chiet tach)) - hanh trinh va dung huong ((dan toan) OR (dan than)) cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc ((hien tach) OR (chiet tach)) - hanh trinh va dung huong ((dan toan) OR (dan than)) cau.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc ((hien tach) or (chiet tach)) - hanh trinh va dung huong ((dan toan) OR (dan than)) cau".
• Adding a wildcard symbol may retrieve word variants: hoc ((hien tach) or (chiet tach)) - hanh trinh va dung huong ((dan toan) OR (dan than)) cau*.