Perhaps you should try some spelling variations:
hien xanh » hien hanh, hien nhanh, chieu xanh
hanh dung » thanh dung, anh dung, hanh dong
dong cong » duong cong, dung cong, dang cong
van thanh » ban thanh, van tuan
dung cua » dung luan, dung cho
cua dong » chua dong, cua cong, cua dang
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: hoc hien xanh - hanh dung cua dong cong ((van thanh) OR (tap toan)) cau~.
• Adding a wildcard symbol may retrieve word variants: hoc hien xanh - hanh dung cua dong cong ((van thanh) or (tap toan)) cau*.