Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
su triet » su viet, su tien, ve triet
tu sach » thu sach, su sach, te sach
sach vu » sach va, sach tu, sach uu
vu nang » vuc nang, va nang, vu dang
nang ma » tang ma, sang ma, nang cao
xuc van » duc van, luc van, vuc van
hanh ki » hanh vi, hanh ky, hanh kien
va cam » va cham, va cac, va cai
va cao » va cac, va co, va dao
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 ma hoa. hieu ((va cam) or (va cao)) xuc van hanh ki su triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach vu nang ma hoa. hieu ((va cam) OR (va cao)) xuc van hanh ki su triet.
• Adding a wildcard symbol may retrieve word variants: tu sach vu nang ma hoa. hieu ((va cam) or (va cao)) xuc van hanh ki su triet*.