Perhaps you should try some spelling variations:
nang mai » nang ma, nang tai, lang mai
hieu van » hieu va, thien van, lieu va
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 cau, van bac
cac dat » cac dan, cai dat, cac dai
va hanh » van hanh, va thanh, va danh
va dinh » van dinh, va kinh, va tinh
vai cua » dai cua, hai cua, lai cua
vi 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 mai hoi. hieu van cac dat ((va hanh) or (va dinh)) ((vi cua) OR (vai cua)) vat~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang mai hoi. hieu van cac dat ((va hanh) OR (va dinh)) ((vi cua) OR (vai cua)) vat.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky nang mai hoi. hieu van cac dat ((va hanh) or (va dinh)) ((vi cua) OR (vai cua)) vat".
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang mai hoi. hieu van cac dat ((va hanh) or (va dinh)) ((vi cua) OR (vai cua)) vat*.