Perhaps you should try some spelling variations:
doanh van » doan van, doanh va, doanh ban
cau tren » cu tren, dau tren, ca tren
cham duc » pham duc, cham soc, pham duy
ke trang » ke toan
trang va » tran van, hang va
danh sai » dung sai, danh bat, danh dau
tu sach » thu sach, te sach, tu cach
va cham » va chat, va tham
su sach » so sach, vu sach
hieu va » lieu va, hieu qua
va hoi » xa hoi, va hoc, va hoa

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) OR (su sach)) ke trang va hoi. hieu va cham duc va ((danh sai) or (doanh van)) cau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (su sach)) ke trang va hoi. hieu va cham duc va ((danh sai) OR (doanh van)) cau tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) OR (su sach)) ke trang va hoi. hieu va cham duc va ((danh sai) or (doanh van)) cau tren".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) OR (su sach)) ke trang va hoi. hieu va cham duc va ((danh sai) or (doanh van)) cau tren*.