Perhaps you should try some spelling variations:
nhung cong » thong cong, hang cong, nhung don
thieu sach » chieu sach, thien hach, hieu cach
hoc thieu » toc thieu, hoc hien
canh manh » lanh manh, canh tranh, cach mang
dung cong » dung trong
manh cua » doanh cua, ban cua
van toan » van tuan, van tan, van thanh
dan than » dan chan, ban than, van than

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 thieu sach - canh manh cua ((nhung cong) OR (dung cong)) ((van toan) OR (dan than)) tap~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc thieu sach - canh manh cua ((nhung cong) OR (dung cong)) ((van toan) or (dan than)) tap~".
• Adding a wildcard symbol may retrieve word variants: hoc thieu sach - canh manh cua ((nhung cong) OR (dung cong)) ((van toan) or (dan than)) tap*.