Perhaps you should try some spelling variations:
nhung cong » dung cong, thong cong, hang cong
toc sach » doc sach, thuoc sach, nuoc sach
hoc sach » hoc sinh, hoc cac, hoc anh
cong san » cong tac
san toan » van toan, dan toan, manh toan
toan cau » toan cao, toan ban, toan tap
mang va » mang vua, bang va, dang va

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: theo ((toc sach) OR (hoc sach)) - hanh ((hang va) OR (mang va)) nhung cong san toan cau~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "theo ((toc sach) OR (hoc sach)) - hanh ((hang va) or (mang va)) nhung cong san toan cau~".
• Adding a wildcard symbol may retrieve word variants: theo ((toc sach) OR (hoc sach)) - hanh ((hang va) or (mang va)) nhung cong san toan cau*.