Perhaps you should try some spelling variations:
thieu xanh » chieu xanh, thien anh, thien danh
thanh tung » thanh cong
hieu manh » chieu xanh, hieu nganh, dieu hanh
dang cong » dung cong
tung cua » trung cua, tuong cua, dung cua
cua dang » cua cong, cua ban
tap toan » tap doan, bai toan
tap quan » tac quan, hai quan

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 xanh) OR (hieu manh)) - thanh tung cua dang cong ((tap toan) OR (tap quan)) cao~.
• Adding a wildcard symbol may retrieve word variants: hoc ((thieu xanh) or (hieu manh)) - thanh tung cua dang cong ((tap toan) or (tap quan)) cao*.