Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
nang xa » nang x, lang xa, nang ma
van cam » van nam, van lam, van dam
van cau » van dau, van hau, van chat
va han » va phan, van han, va hanh
tai va » thai va, mai va, tri va
thiet » thieu

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

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