Perhaps you should try some spelling variations:
nang mai » nang ma, nang tai, lang mai
van hanh » van thanh, ban hanh, van anh
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
mai hoi » mai khoi, dai hoi, lai hoi
dau xua » dao xuan, dau luan, dac xuan
dau cua » dai cua, day cua, cau cua
vi cua » vai cua, di cua
le cua » ly 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 qua ((dau xua) OR (dau cua)) van hanh ((vi cua) or (le cua)) tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang mai hoi. hieu qua ((dau xua) OR (dau cua)) van hanh ((vi cua) OR (le cua)) tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky nang mai hoi. hieu qua ((dau xua) OR (dau cua)) van hanh ((vi cua) or (le cua)) tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang mai hoi. hieu qua ((dau xua) OR (dau cua)) van hanh ((vi cua) or (le cua)) tre*.