Perhaps you should try some spelling variations:
thiet tach » chiet tach, thien hach, thuat tach
thong cong » trong cong, tong cong, thong thong
hoc thiet » hoc thieu, hoc thuyet, hoc hien
tranh cua » doanh cua, manh cua
cua thong » cua thuong, cua khong, cua tong
tan toan » tan tran, tap toan, van toan
bai toan » bai tap

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

• Performing a fuzzy search may retrieve terms with similar spellings: hoc thiet tach - canh tranh cua thong cong ((tan toan) or (bai toan)) ban~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc thiet tach - canh tranh cua thong cong ((tan toan) OR (bai toan)) ban*.