Perhaps you should try some spelling variations:
doanh van » doan van, doanh va, doanh ban
cau tren » cu tren, dau tren, ca tren
hieu ve » hieu va, hieu van
ve cham » va cham, ve chat, vu cham
sach ky » sac ky, sach y, sach ty
nang xa » lang xa, nang ma, mang xa
van cau » van dau, van hau, van chat
tu sach » thu sach, su sach, te sach
luc va » duc va, loc 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 ky ((nang xa) OR (nang x)) hoi. hieu ve cham ((luc va) or (tuc va)) doanh van cau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky ((nang xa) OR (nang x)) hoi. hieu ve cham ((luc va) OR (tuc va)) doanh van cau tren*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky ((nang xa) OR (nang x)) hoi. hieu ve cham ((luc va) or (tuc va)) doanh van cau tren*".