Perhaps you should try some spelling variations:
doanh van » doan van, doanh va, doanh ban
hieu quan » lieu quan, thien quan, lien quan
sach thu » sach thue, sach thieu, sach tham
thu nang » thi nang, thu hang, thu bang
van cuu » van cau, van chu, van cu
tu sach » thu sach, su sach, te sach
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 thu nang xa hoi. ((hieu qua) or (hieu quan)) cam ((xuc va) OR (tuc va)) doanh van cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach thu nang xa hoi. ((hieu qua) OR (hieu quan)) cam ((xuc va) OR (tuc va)) doanh van cuu tre*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach thu nang xa hoi. ((hieu qua) or (hieu quan)) cam ((xuc va) OR (tuc va)) doanh van cuu tre*".