Perhaps you should try some spelling variations:
nhung cong » dung cong, thong cong, nhung don
hieu xanh » chieu xanh, hieu manh, hieu nganh
tranh cua » doanh cua, manh cua
hang cong » dang cong, hang nong, bang cong
chinh cau » chinh chau, chinh ca, chinh can
doc hieu » toc thieu, hoc thieu, hoc hien
chan cau » phan cau, can cau, nhanh cau

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 xanh - canh tranh cua ((nhung cong) OR (hang cong)) dan ((chan cau) OR (chinh cau))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "doc hieu xanh - canh tranh cua ((nhung cong) or (hang cong)) dan ((chan cau) OR (chinh cau))~".
• Adding a wildcard symbol may retrieve word variants: doc hieu xanh - canh tranh cua ((nhung cong) or (hang cong)) dan ((chan cau) OR (chinh cau))*.