Perhaps you should try some spelling variations:
nuoc sach » nguoi sach, cuoc cach, cuon sach
hoc sach » hoc sinh, hoc cac, hoc anh
phuc van » thuc van, phuc va, khuc van
chuc van » chu van, chuc va, thuc van
hanh dai » hanh tai, hanh dao, vanh dai
hieu ve » hieu va, hieu van
cua tre » cua te, cuu tre, cua triet
nang o » nang co, nang ho, nang ro
ve cau » ke cau, va cau, ve cac
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: ((nuoc sach) or (hoc sach)) ky nang o hoi. hieu ve cau ((phuc van) OR (chuc van)) hanh dai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((nuoc sach) OR (hoc sach)) ky nang o hoi. hieu ve cau ((phuc van) OR (chuc van)) hanh dai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((nuoc sach) or (hoc sach)) ky nang o hoi. hieu ve cau ((phuc van) OR (chuc van)) hanh dai cua tre".
• Adding a wildcard symbol may retrieve word variants: ((nuoc sach) or (hoc sach)) ky nang o hoi. hieu ve cau ((phuc van) OR (chuc van)) hanh dai cua tre*.