Perhaps you should try some spelling variations:
nhung cong » dung cong, thong cong, hang cong
hien sach » dien sach, kien sach, thien hach
cua nhung » va nhung
canh van » anh van, can van, cach van
cong ban » cong bang, cong san, cong tan
ban toan » bai toan, ban than, van toan
toan cao » toan ban, toan 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 hien sach - ((canh van) or (cach mang)) cua nhung cong ban toan cao~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc hien sach - ((canh van) OR (cach mang)) cua nhung cong ban toan cao*.