Perhaps you should try some spelling variations:
cam thuyet » bai thuyet, bam huyet, cac tuyet
nang tai » hang tai, tang tai, sang tai
tu sach » thu sach, su sach, te sach
hieu va » lieu va, hieu qua
va nang » van nang, da nang, cam nang
tai cua » thai cua, tai cuc, tri cua
cua tre » cua te, cuu tre, cua triet
y nang » ky nang, ly nang, v nang
va cam » va cham, va cac, va cao
x hoi » o hoi, x ho, 5 hoi

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach y nang ((x hoi) or (xa hoi)). hieu va cam thuyet va nang tai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach y nang ((x hoi) OR (xa hoi)). hieu va cam thuyet va nang tai cua tre.
• Adding a wildcard symbol may retrieve word variants: tu sach y nang ((x hoi) or (xa hoi)). hieu va cam thuyet va nang tai cua tre*.