Perhaps you should try some spelling variations:
thieu nien » thien nhien
hieu vien » hieu hien, hieu viec, hieu tieng
tu sach » thu sach, su sach, te sach
bach tu » bach thu, cach tu, bac tu
vai cua » dai cua, hai cua, bai cua
lai cua » dai cua, hai cua, lai chau
y nang » ky nang, ly nang, v nang
x hoi » xa hoi, o hoi, x ho

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 x hoi. ((hieu vien) or (thieu nien)) bach tu cac dan ((vai cua) OR (lai cua)) tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach y nang x hoi. ((hieu vien) OR (thieu nien)) bach tu cac dan ((vai cua) OR (lai cua)) tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach y nang x hoi. ((hieu vien) or (thieu nien)) bach tu cac dan ((vai cua) OR (lai cua)) tre".
• Adding a wildcard symbol may retrieve word variants: tu sach y nang x hoi. ((hieu vien) or (thieu nien)) bach tu cac dan ((vai cua) OR (lai cua)) tre*.