Perhaps you should try some spelling variations:
vien sau » vien dai, vien da, nien su
ban hanh » ban hang
sach vu » sach va, sach tu, sach uu
kien su » nien su, tien su, bien sua
duc ban » duc tan, duc van, dua ban
cao duc » dao duc, cao suc, giao duc
vu sach » vu bach, su sach, vu khach
hieu va » lieu va, hieu qua
tang ma » mang may, tang van
nang ma » sang ma, nang cao, mang may
va cao » va cac, va co, va dao

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: vu sach vu ((nang ma) or (tang ma)) hoi. hieu va cao duc ban hanh ((kien su) OR (vien sau)) triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: vu sach vu ((nang ma) OR (tang ma)) hoi. hieu va cao duc ban hanh ((kien su) OR (vien sau)) triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "vu sach vu ((nang ma) or (tang ma)) hoi. hieu va cao duc ban hanh ((kien su) OR (vien sau)) triet".
• Adding a wildcard symbol may retrieve word variants: vu sach vu ((nang ma) or (tang ma)) hoi. hieu va cao duc ban hanh ((kien su) OR (vien sau)) triet*.