Perhaps you should try some spelling variations:
thuong cong » thong cong, thuong con, thuong dong
chiet tach » chieu sach
canh trinh » canh tranh, hanh trinh, canh tinh
hoc chiet » hoc thiet, hoc nhiet, hoc hien
trinh va » trinh van, trinh vat, trinh ve
dan toan » van toan, manh toan, xuan toan
dan than » dan chan, ban than, van than

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

• Performing a fuzzy search may retrieve terms with similar spellings: hoc chiet tach - canh trinh va thuong cong ((dan toan) or (dan than)) ban~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc chiet tach - canh trinh va thuong cong ((dan toan) OR (dan than)) ban.
• Adding a wildcard symbol may retrieve word variants: hoc chiet tach - canh trinh va thuong cong ((dan toan) or (dan than)) ban*.