Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
sach vu » sach va, sach tu, sach uu
xuc van » duc van, luc van, vuc van
tu sach » thu sach, su sach, te sach
nang ma » tang ma, sang ma, nang cao
vu nang » vuc nang, va nang, vu dang
va cam » va cham, va cac, va cai
va cao » va cac, va co, va dao
ma hoi » mai hoi, xa hoi, ma hoa

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