Perhaps you should try some spelling variations:
van thanh » ban thanh, van tuan
van hanh » ban hanh, van anh, van ban
va triet » va thiet, va trien, ve triet
tu sach » thu sach, su sach, te sach
ty dang » ky dang, ty hang, ty dong
hieu va » lieu va, hieu qua
cac tac » cac toc, cac bac, cac dac

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 ((ty dang) OR (ty xang)) xa hoi. hieu va cac tac ((van hanh) or (van thanh)) hoi va triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ((ty dang) OR (ty xang)) xa hoi. hieu va cac tac ((van hanh) OR (van thanh)) hoi va triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ((ty dang) OR (ty xang)) xa hoi. hieu va cac tac ((van hanh) or (van thanh)) hoi va triet".
• Adding a wildcard symbol may retrieve word variants: tu sach ((ty dang) OR (ty xang)) xa hoi. hieu va cac tac ((van hanh) or (van thanh)) hoi va triet*.