Perhaps you should try some spelling variations:
hieu manh » chieu xanh, hieu nganh, dieu hanh
tranh cua » doanh cua, manh cua
dung cong » dung trong
hach toan » thanh toan, manh toan
doc hieu » toc thieu, hoc thieu, hoc hien
cua dung » cua dang, cua dong, qua dung
tap toan » tap doan, tap quan, bai toan

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: doc hieu manh - canh tranh cua dung cong ((hach toan) OR (tap toan)) cao~.
• Adding a wildcard symbol may retrieve word variants: doc hieu manh - canh tranh cua dung cong ((hach toan) or (tap toan)) cao*.