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