Perhaps you should try some spelling variations:
chieu tinh » trieu tinh, lieu tinh, chau tinh
dang quang » dung quang, nang quan
hieu manh » chieu xanh, hieu nganh, dieu hanh
tranh cua » doanh cua, manh cua
dang hung » manh hung, dang cong, van hung
tap toan » tap doan, tap quan, bai toan
toan ban » van ban

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 manh) or (chieu tinh)) - canh tranh cua ((dang hung) OR (dang quang)) tap toan ban~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc ((hieu manh) OR (chieu tinh)) - canh tranh cua ((dang hung) OR (dang quang)) tap toan ban.
• The words AND, OR and NOT may confuse the search; try adding quotes: "doc ((hieu manh) or (chieu tinh)) - canh tranh cua ((dang hung) OR (dang quang)) tap toan ban".
• Adding a wildcard symbol may retrieve word variants: doc ((hieu manh) or (chieu tinh)) - canh tranh cua ((dang hung) OR (dang quang)) tap toan ban*.