Perhaps you should try some spelling variations:
thuoc sach » hoc sach, nuoc sach, thuat sach
su sach » so sach, vu sach
hieu va » lieu va, hieu qua
thue va » thuc va, thuyet va, thuc vat
van dai » vanh dai, van dao, van hai
cua tre » cua te, cuu tre, cua triet
nang o » nang co, nang ho, nang ro
va nam » van nam, ha nam, va nay
thu va » thuc va, tu va, thu ha
o hoi » co hoi, o hoc, o hai

You may be able to get more results by adjusting your search query.

• If you are trying to use Boolean operators, they must be ALL CAPS: ((thuoc sach) OR (su sach)) ky nang o hoi. hieu va nam ((thu va) OR (thue va)) van dai cua tre~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((thuoc sach) or (su sach)) ky nang o hoi. hieu va nam ((thu va) OR (thue va)) van dai cua tre~".
• Adding a wildcard symbol may retrieve word variants: ((thuoc sach) or (su sach)) ky nang o hoi. hieu va nam ((thu va) OR (thue va)) van dai cua tre*.