Perhaps you should try some spelling variations:
hoa thiet » hoc thiet, toan thiet, hoa viet
hieu van » hieu va, thien van, lieu va
ha thiet » va thiet, ho thiet, hanh thiet
hanh lam » thanh lap, hanh kem, hanh va
chat huu » pham huu
hieu ve » hieu va
sach ky » sac ky, sach y, sach ty
va hanh » van hanh, va thanh, va danh
nang xa » nang x, lang xa, nang ma
so sach » so sanh, bo sach, co sach
huu va » cuu va, tuu va

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

• Performing a fuzzy search may retrieve terms with similar spellings: so sach ky nang xa hoi. ((hieu ve) or (hieu van)) chat huu va hanh lam ((ha thiet) OR (hoa thiet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach ky nang xa hoi. ((hieu ve) OR (hieu van)) chat huu va hanh lam ((ha thiet) OR (hoa thiet)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sach ky nang xa hoi. ((hieu ve) or (hieu van)) chat huu va hanh lam ((ha thiet) OR (hoa thiet))".
• Adding a wildcard symbol may retrieve word variants: so sach ky nang xa hoi. ((hieu ve) or (hieu van)) chat huu va hanh lam ((ha thiet) OR (hoa thiet))*.