Perhaps you should try some spelling variations:
thieu nien » thien nhien
cac nuoc » cap nuoc, hoc nuoc, dat nuoc
nien cac » vien cac, dien cac, bien cac
thu sach » tu sach, thuat sach, thuoc sach
xay hoi » xa hoi, tay hoi, cay phoi
ky dang » ky nang, ky danh
va hanh » van hanh, va thanh, ban hanh
va danh » va dinh, va dan, dia danh
ty dang » ty xang, ty hang, ty dong
cua tre » cua te, cuu tre, cua triet

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

• Performing a fuzzy search may retrieve terms with similar spellings: thu sach ((ty dang) or (ky dang)) xay hoi. thieu nien cac nuoc ((va hanh) OR (va danh)) dai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach ((ty dang) OR (ky dang)) xay hoi. thieu nien cac nuoc ((va hanh) OR (va danh)) dai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sach ((ty dang) or (ky dang)) xay hoi. thieu nien cac nuoc ((va hanh) OR (va danh)) dai cua tre".
• Adding a wildcard symbol may retrieve word variants: thu sach ((ty dang) or (ky dang)) xay hoi. thieu nien cac nuoc ((va hanh) OR (va danh)) dai cua tre*.