Perhaps you should try some spelling variations:
hanh tranh » canh tranh, hanh trinh, hanh trang
nhung cong » dung cong, thong cong, hang cong
chi xanh » chi anh, chi danh, chi hanh
tranh va » tranh van, trang va, trinh va
tap toan » tap doan, tap quan
bai toan » bai tap
doi chi » doi khi

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 va nhung cong ((tap toan) OR (bai toan)) cao~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "doi chi xanh - hanh tranh va nhung cong ((tap toan) OR (bai toan)) cao".
• Adding a wildcard symbol may retrieve word variants: doi chi xanh - hanh tranh va nhung cong ((tap toan) OR (bai toan)) cao*.