Perhaps you should try some spelling variations:
ban hanh » ban hang
tru nang » tra nang, tri nang, truc nano
tu sach » thu sach, te sach, tu cach
cuc ban » cua ban, cac ban, cuu ban
nam cuc » nam cac, nam cua, nam thuc
hieu va » lieu va, hieu qua
cua tre » cua te, cuu tre, cua triet
su sach » so sach, vu sach
va nam » van nam, ha nam, va nay
vi cua » vai cua, di cua
co hoi » co hoc, co loi
o hoi » o hoc, o hai, o hoa

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) or (su sach)) tru nang ((o hoi) OR (co hoi)). hieu va nam cuc ban hanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (su sach)) tru nang ((o hoi) OR (co hoi)). hieu va nam cuc ban hanh vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) or (su sach)) tru nang ((o hoi) OR (co hoi)). hieu va nam cuc ban hanh vi cua tre".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (su sach)) tru nang ((o hoi) OR (co hoi)). hieu va nam cuc ban hanh vi cua tre*.