Perhaps you should try some spelling variations:
ban hanh » ban hang
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
ky dang » ky nang, ky danh
dang xa » dang xay, lang xa, dang ha
van cac » van hac, van cau, dan cac
van bac » van bao, van hac, dan bac
vai cua » dai cua, hai cua, lai cua
cua tre » cua te, cuu tre, cua triet

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 dang xa hoi. hieu ((van cac) OR (van bac)) xuc ((van ban) or (ban hanh)) vai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky dang xa hoi. hieu ((van cac) OR (van bac)) xuc ((van ban) OR (ban hanh)) vai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky dang xa hoi. hieu ((van cac) OR (van bac)) xuc ((van ban) or (ban hanh)) vai cua tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ky dang xa hoi. hieu ((van cac) OR (van bac)) xuc ((van ban) or (ban hanh)) vai cua tre*.