Perhaps you should try some spelling variations:
thu sach » thuat sach, thuoc sach, thu hoach
doi nang » dai nang, hoi nang, voi nang
ban hanh » ban hang
hieu van » hieu va, thien van, lieu va
tu sach » su sach, te sach, tu cach
van cam » van nam, van lam, van cau
vai cua » dai cua, hai cua, lai cua
cua tre » cua te, cuu tre, cua triet
nang o » nang co, nang ho, nang ro
va dan » ca dan, va dao, va dau
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)) doi nang o hoi. hieu van cam xuc ((ban hanh) or (va dan)) vai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((thu sach) OR (tu sach)) doi nang o hoi. hieu van cam xuc ((ban hanh) OR (va dan)) vai cua tre*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((thu sach) OR (tu sach)) doi nang o hoi. hieu van cam xuc ((ban hanh) or (va dan)) vai cua tre*".