Perhaps you should try some spelling variations:
thieu nien » thien nhien
nien cac » vien cac, dien cac, bien cac
cac nuoc » cap nuoc, hoc nuoc, dat nuoc
hanh tai » thanh tai, hang tai, han tai
su triet » su viet, su tien, ve triet
tu sach » thu sach, su sach, te sach
nang xa » nang x, lang xa, nang ma
va hanh » van hanh, va thanh, va danh
y nang » ky nang, ly nang, v nang

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 y nang xa hoi. thieu nien cac nuoc va hanh tai ((su triet) or (va thiet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach y nang xa hoi. thieu nien cac nuoc va hanh tai ((su triet) OR (va thiet)).
• Adding a wildcard symbol may retrieve word variants: tu sach y nang xa hoi. thieu nien cac nuoc va hanh tai ((su triet) or (va thiet))*.