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
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
cac tuc » cac toc, cac tu, cac tac
va hanh » va thanh, va danh, ban hanh

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 tuc ((va hanh) OR (van hanh)) tai ((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 tuc ((va hanh) OR (van hanh)) tai ((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 tuc ((va hanh) OR (van hanh)) tai ((su triet) or (va thiet))".
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang xa hoi. thieu nien cac tuc ((va hanh) OR (van hanh)) tai ((su triet) or (va thiet))*.