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