Perhaps you should try some spelling variations:
ban hanh » ban hang
van hanh » van thanh, van anh, van ban
cac duc » cac du, cao duc, cac dac
gia cua » gian cua, giau cua, gia cuc
cua tre » cua te, cuu tre, cua triet
sach ky » sach y, sach ty, sach kem
hieu ve » hieu va, hieu van
sac ky » cac ky, sai ky
ve cac » va cac, vien cac
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) or (sac ky)) nang x hoi. hieu ve cac duc ((van hanh) OR (ban hanh)) gia cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sach ky) OR (sac ky)) nang x hoi. hieu ve cac duc ((van hanh) OR (ban hanh)) gia cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu ((sach ky) or (sac ky)) nang x hoi. hieu ve cac duc ((van hanh) OR (ban hanh)) gia cua tre".
• Adding a wildcard symbol may retrieve word variants: tu ((sach ky) or (sac ky)) nang x hoi. hieu ve cac duc ((van hanh) OR (ban hanh)) gia cua tre*.