Perhaps you should try some spelling variations:
doanh van » doan van, doanh va, doanh ban
va doanh » van doanh, vay doanh, va danh
tu sach » thu sach, su sach, te sach
ky sang » ky nang, ky dang, ky tang
van cua » vang cua, ban cua, dan cua
sach ky » sac ky, sach y, sach ty
va cao » va cac, va co, va dao
ve cam » ve cham, ve cac, va cam
ma hoi » mai hoi, ma hoa, me hoi
cua te » cua tu

You may be able to get more results by adjusting your search query.

• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky sang ((ma hoi) OR (xa hoi)). hieu ((ve cam) OR (va cao)) duc va doanh van cua te~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky sang ((ma hoi) OR (xa hoi)). hieu ((ve cam) or (va cao)) duc va doanh van cua te~".
• Adding a wildcard symbol may retrieve word variants: tu sach ky sang ((ma hoi) OR (xa hoi)). hieu ((ve cam) or (va cao)) duc va doanh van cua te*.