Perhaps you should try some spelling variations:
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
mai hoi » mai khoi, lai hoi, mai doi
dai hoi » dai hoc, dai hai, dai moi
bac mai » bach mai, bac dai, ban mai
va hanh » van hanh, va thanh, va danh
ma hoi » xa hoi, ma hoa, me hoi
va bac » van bac, va cac, va bai
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: tu sach ky nang ((((ma hoi) OR (mai hoi))) or (dai hoi)). lieu va bac mai va hanh vi cua vat~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang ((((ma hoi) OR (mai hoi))) OR (dai hoi)). lieu va bac mai va hanh vi cua vat.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky nang ((((ma hoi) OR (mai hoi))) or (dai hoi)). lieu va bac mai va hanh vi cua vat".
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang ((((ma hoi) OR (mai hoi))) or (dai hoi)). lieu va bac mai va hanh vi cua vat*.