Perhaps you should try some spelling variations:
chieu xanh » chieu sach, chieu sang, chieu tinh
nhung cong » thong cong, hang cong, nhung don
hiem ngan » kim ngan, viem gan
hanh tang » hanh trang, anh tang, hanh mang
tang luan » dung luan
dung cong » dung trong
tap toan » tap doan, tap quan, bai toan
toan cau » 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: theo ((hiem ngan) or (chieu xanh)) - hanh tang luan ((nhung cong) OR (dung cong)) tap toan cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: theo ((hiem ngan) OR (chieu xanh)) - hanh tang luan ((nhung cong) OR (dung cong)) tap toan cau*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "theo ((hiem ngan) or (chieu xanh)) - hanh tang luan ((nhung cong) OR (dung cong)) tap toan cau*".