Perhaps you should try some spelling variations:
ban danh » ban doanh, ban hanh, ban dan
sach vu » sach va, sach tu, sach uu
kien de » kien dien
kien ve » kien va, dien ve, kien viet
duc ban » duc tan, duc van, dua ban
vu sach » vu bach, su sach, vu khach
hieu va » lieu va, hieu qua
tang ma » mang may, tang van
cac duc » cac du, cao duc, cac dac

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