Perhaps you should try some spelling variations:
nhung cong » dung cong, thong cong, hang cong
tieu xanh » tieu danh, chieu xanh, dieu hanh
hanh tang » hanh trang, anh tang, hanh mang
cua nhung » va nhung
tang cua » mang cua, hang cua, tang luan
van toan » van tuan, van tan, van thanh
tap toan » tap doan, tap quan
bai toan » bai tap

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 tieu xanh - hanh tang cua nhung cong ((van toan) OR (((tap toan) OR (bai toan)))) tap~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "theo tieu xanh - hanh tang cua nhung cong ((van toan) or (((tap toan) OR (bai toan)))) tap~".
• Adding a wildcard symbol may retrieve word variants: theo tieu xanh - hanh tang cua nhung cong ((van toan) or (((tap toan) OR (bai toan)))) tap*.