Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
hieu van » hieu va, thien van, lieu va
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
vai cua » dai cua, hai cua, lai cua
ban so » ban do, ban co, ban bo
so van » su van, vo van
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 x ho. hieu van ban so van hanh ((vi cua) or (vai cua)) triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang x ho. hieu van ban so van hanh ((vi cua) OR (vai cua)) triet.
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang x ho. hieu van ban so van hanh ((vi cua) or (vai cua)) triet*.