Perhaps you should try some spelling variations:
thu sach » thuat sach, thuoc sach, thu hoach
hanh vai » hanh vi, hanh va, hanh tai
vai cua » dai cua, hai cua, lai cua
hieu va » lieu va, hieu qua
va tham » van tham, va cham, va thanh
tu sach » su sach, te sach, tu cach
cua tre » cua te, cuu tre, cua triet
nang o » nang co, nang ho, nang ro
v nang » va nang, vu nang, van nang
luc va » duc va, tuc va
loc va » hoc va
o hoi » co hoi, o hoc, o hai

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: ((thu sach) OR (tu sach)) v nang o hoi. hieu va tham ((luc va) or (loc va)) hanh vai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((thu sach) OR (tu sach)) v nang o hoi. hieu va tham ((luc va) OR (loc va)) hanh vai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((thu sach) OR (tu sach)) v nang o hoi. hieu va tham ((luc va) or (loc va)) hanh vai cua tre".
• Adding a wildcard symbol may retrieve word variants: ((thu sach) OR (tu sach)) v nang o hoi. hieu va tham ((luc va) or (loc va)) hanh vai cua tre*.