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, dai hoi, lai hoi
van cac » van hac, van bac, dan cac
van cau » van dau, van hau, van chat
va hanh » van hanh, va thanh, va danh
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: tu sach ky nang ((ma hoi) or (mai hoi)). hieu ((van cac) OR (van cau)) dat 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)). hieu ((van cac) OR (van cau)) dat 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)). hieu ((van cac) OR (van cau)) dat va hanh vi cua vat".
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang ((ma hoi) or (mai hoi)). hieu ((van cac) OR (van cau)) dat va hanh vi cua vat*.