Perhaps you should try some spelling variations:
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
anh via » anh bia, anh viet, anh giao
duc van » duc va, duc tan, duc manh
cac duc » cac du, cao duc, cac dac
cua tre » cua te, cuu tre, cua triet
hieu ve » hieu va, hieu van
anh va » hanh va
ve cac » va cac, vien cac
o hai » co hai, so hai, o lai
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 sach ky nang ((x hoi) or (o hai)). hieu ve cac duc van ((anh via) or (anh va)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang ((x hoi) OR (o hai)). hieu ve cac duc van ((anh via) OR (anh va)) cua tre.
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang ((x hoi) or (o hai)). hieu ve cac duc van ((anh via) or (anh va)) cua tre*.