Perhaps you should try some spelling variations:
hieu vien » hieu hien, thieu nien, hieu tieng
hieu viec » nhieu viec, hieu ve, sieu viet
su triet » su viet, su tien, ve triet
vat hanh » vat thanh, van hanh, va hanh
sach ky » sac ky, sach y, sach ty
cac hoc » cach hoc, cac hop, cac toc
bac hoc » bai hoc, bac ho
nang xa » nang x, lang xa, nang ma
su sach » so sach, vu sach
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 ky nang xa hoi. ((hieu vien) or (hieu viec)) ((cac hoc) OR (bac hoc)) vat hanh vi su triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ky nang xa hoi. ((hieu vien) OR (hieu viec)) ((cac hoc) OR (bac hoc)) vat hanh vi su triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ky nang xa hoi. ((hieu vien) or (hieu viec)) ((cac hoc) OR (bac hoc)) vat hanh vi su triet".
• Adding a wildcard symbol may retrieve word variants: su sach ky nang xa hoi. ((hieu vien) or (hieu viec)) ((cac hoc) OR (bac hoc)) vat hanh vi su triet*.