Perhaps you should try some spelling variations:
hanh tai » thanh tai, hang tai, han tai
ban hanh » ban hang
hieu ve » hieu va, hieu van
tai cua » thai cua, tai cuc, tri cua
duc ban » duc tan, duc van, dua ban
cam duc » cam xuc, cao duc, pham duc
ve cam » ve cham, ve cac, va cam
san ky » sang ky, van ky, ban ky
co hai » co dai, co hoi, o hai
dan ky » van ky
cua cu » cua chu, cua cau, cua su
x hoi » xa hoi, o hoi, x ho

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu ((san ky) OR (dan ky)) nang ((x hoi) or (co hai)). hieu ve cam duc ban hanh tai cua cu~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((san ky) OR (dan ky)) nang ((x hoi) OR (co hai)). hieu ve cam duc ban hanh tai cua cu.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu ((san ky) OR (dan ky)) nang ((x hoi) or (co hai)). hieu ve cam duc ban hanh tai cua cu".
• Adding a wildcard symbol may retrieve word variants: tu ((san ky) OR (dan ky)) nang ((x hoi) or (co hai)). hieu ve cam duc ban hanh tai cua cu*.