Perhaps you should try some spelling variations:
chieu xanh » chieu sach, chieu sang, chieu tinh
canh trinh » canh tranh, hanh trinh, canh tinh
nhung cong » thong cong, hang cong, nhung don
hien xanh » hien hanh, hien nhanh, hien khanh
dung cong » dung trong
trinh va » trinh van, trinh vat, trinh ve
tap toan » tap doan, tap quan, bai toan
toan cao » toan ban, toan tap

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

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