Perhaps you should try some spelling variations:
thu sach » thuat sach, thuoc sach, thu hoach
hanh dai » hanh tai, hanh dao, vanh dai
tu sach » su sach, te sach, tu cach
cua tre » cuu tre, cua triet, dua tren
va hanh » van hanh, va thanh, va danh
cao luc » bao luc, cao duc, cao suc
hieu va » lieu va, hieu qua
va cao » va cac, va co, va dao
luc va » duc va, tuc va, loc va
nang o » nang co, nang ho, nang ro
cua te » cua tu
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) or (thu sach)) ky nang o hoi. hieu va cao luc va hanh dai ((cua tre) or (cua te))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (thu sach)) ky nang o hoi. hieu va cao luc va hanh dai ((cua tre) OR (cua te)).
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (thu sach)) ky nang o hoi. hieu va cao luc va hanh dai ((cua tre) or (cua te))*.