Perhaps you should try some spelling variations:
lanh tranh » canh tranh, lan tranh, hanh trinh
tranh chua » tranh cua, trinh chuan, tranh chap
chua xang » chua nang, chu bang, chua dong
bang cong » dang cong, bang song, dung cong
hang cong » dang cong, hang nong, thanh cong
bai toan » bai tap
toan cao » toan ban, toan tap
chuc » thuc, chu, phuc

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

• Performing a fuzzy search may retrieve terms with similar spellings: theo ((chua xang) or (chuc nang)) - lanh tranh chua ((bang cong) OR (hang cong)) bai toan cao~.
• If you are trying to use Boolean operators, they must be ALL CAPS: theo ((chua xang) OR (chuc nang)) - lanh tranh chua ((bang cong) OR (hang cong)) bai toan cao.
• The words AND, OR and NOT may confuse the search; try adding quotes: "theo ((chua xang) or (chuc nang)) - lanh tranh chua ((bang cong) OR (hang cong)) bai toan cao".
• Adding a wildcard symbol may retrieve word variants: theo ((chua xang) or (chuc nang)) - lanh tranh chua ((bang cong) OR (hang cong)) bai toan cao*.