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