Perhaps you should try some spelling variations:
vao truc » vao thuc, cau truc, dao tuc
nang doc » nang luc
van hanh » van thanh, ban hanh, van anh
sach vu » sach va, sach tu, sach uu
su sach » so sach, vu sach
doc hoi » duoc hoi, hoc hoi, doc hai
vu nang » vuc nang, va nang, vu dang
va hanh » va thanh, va danh, ban hanh
va vao » va van, va dao, va bao
va ve » va de, va vi, va vo
va le » va de, vu le

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 vu nang doc hoi. lieu va vao truc ((va hanh) OR (van hanh)) ((va ve) or (va le)) triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach vu nang doc hoi. lieu va vao truc ((va hanh) OR (van hanh)) ((va ve) OR (va le)) triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach vu nang doc hoi. lieu va vao truc ((va hanh) OR (van hanh)) ((va ve) or (va le)) triet".
• Adding a wildcard symbol may retrieve word variants: su sach vu nang doc hoi. lieu va vao truc ((va hanh) OR (van hanh)) ((va ve) or (va le)) triet*.