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 vai » hanh vi, hanh tai, hanh van
su triet » su viet, su tien, ve triet
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
nang xa » nang x, lang xa, nang ma
hanh va » hang va, hanh vi

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 ky nang xa hoi. thieu nien cac nuoc va ((hanh vai) OR (hanh va)) ((su triet) or (va thiet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang xa hoi. thieu nien cac nuoc va ((hanh vai) OR (hanh va)) ((su triet) OR (va thiet)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky nang xa hoi. thieu nien cac nuoc va ((hanh vai) OR (hanh va)) ((su triet) or (va thiet))".
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang xa hoi. thieu nien cac nuoc va ((hanh vai) OR (hanh va)) ((su triet) or (va thiet))*.