Perhaps you should try some spelling variations:
cham chua » kham chua, cha chua, chay chua
qua cham » qua hai, qua cac, va cham
chua ban » chua bang, cua ban, chua dan
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
hanh de » hanh ve, hanh kem
cua tre » cua te, cuu tre, cua triet
anh de » anh d, anh ve, anh du
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 ky nang ((x hoi) or (xa hoi)). hieu qua cham chua ban ((anh de) OR (hanh de)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang ((x hoi) OR (xa hoi)). hieu qua cham chua ban ((anh de) OR (hanh de)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky nang ((x hoi) or (xa hoi)). hieu qua cham chua ban ((anh de) OR (hanh de)) cua tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang ((x hoi) or (xa hoi)). hieu qua cham chua ban ((anh de) OR (hanh de)) cua tre*.