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