Perhaps you should try some spelling variations:
doanh van » doan van, doanh va, doanh ban
tu sach » thu sach, su sach, te sach
nang xa » nang x, nang ma, mang xa
lang xa » lang ha, dang xay, lang van
hieu ve » hieu va, hieu van
ve cham » va cham, ve chat, vu cham
luc van » luoc van, luu van, luc va
duc van » duc va, duc tan, duc manh
van cuu » van cau, van chu, van cu
cuu tre » cua tre, cau tren, cau treo

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 y ((nang xa) or (lang xa)) hoi. hieu ve cham ((luc van) OR (duc van)) doanh van cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach y ((nang xa) OR (lang xa)) hoi. hieu ve cham ((luc van) OR (duc van)) doanh van cuu tre*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach y ((nang xa) or (lang xa)) hoi. hieu ve cham ((luc van) OR (duc van)) doanh van cuu tre*".