Perhaps you should try some spelling variations:
thieu nien » thien nhien
thu sach » thuat sach, thuoc sach, thu hoach
hanh dai » hanh tai, hanh dao, vanh dai
cac nuoc » cap nuoc, hoc nuoc, dat nuoc
nien cac » vien cac, dien cac, bien cac
ky dang » ky nang, ky danh
xay hoi » xa hoi, tay hoi, cay phoi
ty dang » ty xang, ty hang, ty dong
tu sach » su sach, te sach, tu cach
va hanh » van hanh, va thanh, va danh
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) OR (tu sach)) ((ty dang) or (ky dang)) xay hoi. thieu nien cac nuoc va hanh dai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((thu sach) OR (tu sach)) ((ty dang) OR (ky dang)) xay hoi. thieu nien cac nuoc va hanh dai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((thu sach) OR (tu sach)) ((ty dang) or (ky dang)) xay hoi. thieu nien cac nuoc va hanh dai cua tre".
• Adding a wildcard symbol may retrieve word variants: ((thu sach) OR (tu sach)) ((ty dang) or (ky dang)) xay hoi. thieu nien cac nuoc va hanh dai cua tre*.