Perhaps you should try some spelling variations:
sach thien » sach thieu, sach tien, cach thien
thien nang » thien bang, thien dang, trien nang
doanh ban » doanh bat, doanh van, doanh nhan
tu sach » thu sach, su sach, te sach
ban cuu » ban cua, ban cau, ban muu
hieu ve » hieu va, hieu van
nang xa » nang x, lang xa, nang ma
cuu tre » cua tre, cau tren, cau treo
xuc va » duc va, luc va, xac va
tuc va » thuc va, truc va, tuc xa

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 thien nang xa hoi. ((hieu ve) or (hieu qua)) cam ((xuc va) OR (tuc va)) doanh ban cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach thien nang xa hoi. ((hieu ve) OR (hieu qua)) cam ((xuc va) OR (tuc va)) doanh ban cuu tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach thien nang xa hoi. ((hieu ve) or (hieu qua)) cam ((xuc va) OR (tuc va)) doanh ban cuu tre".
• Adding a wildcard symbol may retrieve word variants: tu sach thien nang xa hoi. ((hieu ve) or (hieu qua)) cam ((xuc va) OR (tuc va)) doanh ban cuu tre*.