Perhaps you should try some spelling variations:
hieu nganh » vien nganh, hiem ngan, hieu manh
canh trinh » canh tranh, hanh trinh, canh tinh
cong luong » cong thuong, nang luong, cong dong
hieu xanh » chieu xanh, hieu manh, dieu hanh
trinh van » trinh han, trinh quan, trinh toan
van nhung » van nhuong, va nhung, van hung
cong lang » cong vang, cong quang, cong ngang
than cao » toan cao, thai cao, than cap

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: doc ((hieu xanh) OR (hieu nganh)) - canh trinh van nhung ((cong lang) or (cong luong)) than cao~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc ((hieu xanh) OR (hieu nganh)) - canh trinh van nhung ((cong lang) OR (cong luong)) than cao.
• The words AND, OR and NOT may confuse the search; try adding quotes: "doc ((hieu xanh) OR (hieu nganh)) - canh trinh van nhung ((cong lang) or (cong luong)) than cao".
• Adding a wildcard symbol may retrieve word variants: doc ((hieu xanh) OR (hieu nganh)) - canh trinh van nhung ((cong lang) or (cong luong)) than cao*.