Perhaps you should try some spelling variations:
thiet tach » thien hach, thuat tach
chiet tach » chieu sach
tranh cua » doanh cua, manh cua
dung cong » dung trong
hach toan » thanh toan, manh toan
cua dung » cua dang, cua dong, qua dung
tap toan » tap doan, tap quan, bai toan

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

• If you are trying to use Boolean operators, they must be ALL CAPS: hoc ((thiet tach) OR (chiet tach)) - canh tranh cua dung cong ((tap toan) OR (hach toan)) ban~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc ((thiet tach) OR (chiet tach)) - canh tranh cua dung cong ((tap toan) or (hach toan)) ban~".
• Adding a wildcard symbol may retrieve word variants: hoc ((thiet tach) OR (chiet tach)) - canh tranh cua dung cong ((tap toan) or (hach toan)) ban*.