Perhaps you should try some spelling variations:
hanh tranh » canh tranh, hanh trinh, hanh trang
nhung cong » dung cong, thong cong, hang cong
hien xanh » hien hanh, hien nhanh, chieu xanh
tranh va » tranh van, trang va, trinh va
tan toan » tan tran, van toan, dan toan
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 hien xanh - hanh tranh va nhung cong ((tan toan) OR (((tap toan) OR (tap quan)))) tap~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc hien xanh - hanh tranh va nhung cong ((tan toan) or (((tap toan) OR (tap quan)))) tap~".
• Adding a wildcard symbol may retrieve word variants: hoc hien xanh - hanh tranh va nhung cong ((tan toan) or (((tap toan) OR (tap quan)))) tap*.