Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
nang mai » nang ma, nang tai, lang mai
sach vu » sach va, sach tu, sach uu
xuc van » duc van, luc van, vuc van
va cham » va chat, va tham
tu sach » thu sach, su sach, te sach
mai hoi » mai khoi, dai hoi, lai hoi
vu nang » vuc nang, va nang, vu dang
va cam » va cac, va cao, va cai
vi su » va su, ve su, oi su
ki su » ky su

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 vu nang mai hoi. hieu ((va cam) or (va cham)) xuc van hanh ((vi su) OR (ki su)) triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach vu nang mai hoi. hieu ((va cam) OR (va cham)) xuc van hanh ((vi su) OR (ki su)) triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach vu nang mai hoi. hieu ((va cam) or (va cham)) xuc van hanh ((vi su) OR (ki su)) triet".
• Adding a wildcard symbol may retrieve word variants: tu sach vu nang mai hoi. hieu ((va cam) or (va cham)) xuc van hanh ((vi su) OR (ki su)) triet*.