Perhaps you should try some spelling variations:
tu sach » thu sach, su sach, te sach
vai cua » dai cua, hai cua, lai cua
hieu ve » hieu va, hieu van
cac tu » cac thu, cach tu, tac tu
y nang » ky nang, ly nang, v nang
va dan » ca dan, va dao, va dau
vi cua » di cua
nang o » nang co, nang ho, nang ro
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: tu sach y nang o hoi. hieu ve ((cac tu) or (cac du)) va dan ((vi cua) OR (vai cua)) tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach y nang o hoi. hieu ve ((cac tu) OR (cac du)) va dan ((vi cua) OR (vai cua)) tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach y nang o hoi. hieu ve ((cac tu) or (cac du)) va dan ((vi cua) OR (vai cua)) tre".
• Adding a wildcard symbol may retrieve word variants: tu sach y nang o hoi. hieu ve ((cac tu) or (cac du)) va dan ((vi cua) OR (vai cua)) tre*.