Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
tu sach » thu sach, su sach, te sach
sach ty » sach y, sach tu, sach thu
va hanh » va thanh, va danh, ban hanh
vai cua » dai cua, hai cua, lai cua
nang ma » tang ma, sang ma, nang cao
ty nang » ky nang, ty xang, ty hang
va cao » va co, va dao, va bao
ma hoi » mai hoi, xa hoi, ma hoa

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