Perhaps you should try some spelling variations:
nhung cong » dung cong, thong cong, hang cong
ho chieu » theo chieu, hoc thieu, doi chieu
cong bai » cuong bai, cong hai, cung bai
bai toan » bai tap
toan cao » toan ban, toan tap
cong ky » cuong ky, cong ty, dong ky
hong ky » thong ke

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((ho chieu) or (theo tieu)) sach - thanh ((cong ky) OR (hong ky)) nhung cong bai toan cao~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((ho chieu) OR (theo tieu)) sach - thanh ((cong ky) OR (hong ky)) nhung cong bai toan cao.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((ho chieu) or (theo tieu)) sach - thanh ((cong ky) OR (hong ky)) nhung cong bai toan cao".
• Adding a wildcard symbol may retrieve word variants: ((ho chieu) or (theo tieu)) sach - thanh ((cong ky) OR (hong ky)) nhung cong bai toan cao*.