Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
hieu van » hieu va, thien van, lieu va
lam duc » lam duoc, pham duc, nam duoc
cua tre » cua te, cuu tre, cua triet
va hanh » van hanh, va thanh, va danh
cu tren » tu tren, dua tren
van lam » van nam
y nang » ky nang, ly nang, v nang
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 y nang o hoi. hieu van lam duc ((va dan) or (va hanh)) vi ((cua tre) or (cu tren))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach y nang o hoi. hieu van lam duc ((va dan) OR (va hanh)) vi ((cua tre) OR (cu tren)).
• Adding a wildcard symbol may retrieve word variants: thu sach y nang o hoi. hieu van lam duc ((va dan) or (va hanh)) vi ((cua tre) or (cu tren))*.