Perhaps you should try some spelling variations:
va thanh » gia thanh, ban thanh, va tinh
te sach » toc sach
va hanh » van hanh, va danh, ban hanh
mai hoi » mai khoi, dai hoi, lai hoi
sach ky » sac ky, sach y, sach ty
bac dai » bach mai
va bac » van bac, va cac, va bai
ma hoi » xa hoi, ma hoa, me hoi
vi cua » vai cua, di cua

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

• Performing a fuzzy search may retrieve terms with similar spellings: te sach ky nang ((ma hoi) or (mai hoi)). lieu va bac dai ((va hanh) OR (va thanh)) vi cua vat~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach ky nang ((ma hoi) OR (mai hoi)). lieu va bac dai ((va hanh) OR (va thanh)) vi cua vat.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach ky nang ((ma hoi) or (mai hoi)). lieu va bac dai ((va hanh) OR (va thanh)) vi cua vat".
• Adding a wildcard symbol may retrieve word variants: te sach ky nang ((ma hoi) or (mai hoi)). lieu va bac dai ((va hanh) OR (va thanh)) vi cua vat*.