Perhaps you should try some spelling variations:
nang dai » nang dau, nang tai, lang dai
thu sach » thuat sach, thuoc sach, thu hoach
va hanh » van hanh, va thanh, va danh
tu sach » su sach, te sach, tu cach
dai hoi » dai hoc, dai hai, dai moi
ty nang » ky nang, ty xang, ty hang
va bao » va bai
xuc va » duc va, tuc va, luc va
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) OR (thu sach)) ty nang dai hoi. hieu ((va cac) or (va bao)) xuc va hanh vi cua vat~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (thu sach)) ty nang dai hoi. hieu ((va cac) OR (va bao)) xuc va hanh vi cua vat.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) OR (thu sach)) ty nang dai hoi. hieu ((va cac) or (va bao)) xuc va hanh vi cua vat".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) OR (thu sach)) ty nang dai hoi. hieu ((va cac) or (va bao)) xuc va hanh vi cua vat*.