Perhaps you should try some spelling variations:
vanh dai » van dai, vanh tai, lanh dao
tu sach » thu sach, te sach, tu cach
su sach » so sach, vu sach
thuc va » thuc vat, thuc dan, thuc day
va vanh » va van, va danh, va hanh
cua tre » cua te, cuu tre, cua triet
nang o » nang co, nang ho, nang ro
va nam » van nam, va nay
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: ((tu sach) OR (su sach)) ky nang o hoi. hieu ((va nam) OR (ha nam)) thuc va vanh dai cua tre~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) or (su sach)) ky nang o hoi. hieu ((va nam) OR (ha nam)) thuc va vanh dai cua tre~".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (su sach)) ky nang o hoi. hieu ((va nam) OR (ha nam)) thuc va vanh dai cua tre*.