Perhaps you should try some spelling variations:
nhung cong » dung cong, thong cong, nhung don
hien xanh » hien hanh, hien nhanh, chieu xanh
lieu tinh » trieu tinh, diep tinh, bien tinh
hang cong » dang cong, hang nong, bang cong
tranh va » tranh van, trang va, trinh va
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 (lieu tinh)) - canh tranh va ((nhung cong) OR (hang cong)) tap toan cao~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc ((hien xanh) OR (lieu tinh)) - canh tranh va ((nhung cong) OR (hang cong)) tap toan cao.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc ((hien xanh) or (lieu tinh)) - canh tranh va ((nhung cong) OR (hang cong)) tap toan cao".
• Adding a wildcard symbol may retrieve word variants: hoc ((hien xanh) or (lieu tinh)) - canh tranh va ((nhung cong) OR (hang cong)) tap toan cao*.