Perhaps you should try some spelling variations:
thieu nien » thien nhien
nien cac » vien cac, dien cac, bien cac
su triet » su viet, su tien, ve triet
su sach » so sach, vu sach
ty nang » ky nang, ty hang, ly nang
toc van » hoc van, tac van, oc van
vi su » va su, ve su, ki su

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: su sach ((ty nang) or (ty xang)) xa hoi. thieu nien cac ((toc van) OR (toc san)) hanh vi su triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ((ty nang) OR (ty xang)) xa hoi. thieu nien cac ((toc van) OR (toc san)) hanh vi su triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ((ty nang) or (ty xang)) xa hoi. thieu nien cac ((toc van) OR (toc san)) hanh vi su triet".
• Adding a wildcard symbol may retrieve word variants: su sach ((ty nang) or (ty xang)) xa hoi. thieu nien cac ((toc van) OR (toc san)) hanh vi su triet*.