Perhaps you should try some spelling variations:
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
ve bac » ve cac, ve ban, he bac
bo van » vo van, so van, do van
ve bao » te bao, va bao
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. hieu ((ve bac) OR (ve bao)) bo van ((hanh vi) or (hanh de)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang x hoi. hieu ((ve bac) OR (ve bao)) bo van ((hanh vi) OR (hanh de)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky nang x hoi. hieu ((ve bac) OR (ve bao)) bo van ((hanh vi) or (hanh de)) cua tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang x hoi. hieu ((ve bac) OR (ve bao)) bo van ((hanh vi) or (hanh de)) cua tre*.