Perhaps you should try some spelling variations:
hanh trinh » canh tranh, hanh chinh
hanh tranh » canh tranh, hanh trang, lanh tranh
hong cuong » hong vuong, hung cuong, thong chuong
chi xanh » chi anh, chi danh, chi hanh
tap toan » tap doan, tap quan
bai toan » bai tap
doi chi » doi khi
va hong » va thong, va huong, va phong

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

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