Perhaps you should try some spelling variations:
nang mai » nang ma, nang tai, lang mai
van hanh » van thanh, ban hanh, van anh
su sach » so sach, vu sach
sach ky » sac ky, sach y, sach ty
mai hoi » mai khoi, dai hoi, lai hoi
hieu va » lieu va, hieu qua
va hanh » va thanh, va danh, ban hanh
va hai » van hai, va chai, va khai
hai xu » thai xu, hai vu, dai xu
va cau » van cau, va cac, va dau

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: su sach ky nang mai hoi. hieu va hai xu ((va hanh) OR (van hanh)) va cau thi~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ky nang mai hoi. hieu va hai xu ((va hanh) OR (van hanh)) va cau thi".
• Adding a wildcard symbol may retrieve word variants: su sach ky nang mai hoi. hieu va hai xu ((va hanh) OR (van hanh)) va cau thi*.