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
sach ky » sac ky, sach y, sach ty
nang ma » tang ma, sang ma, mang may
hieu ve » hieu va, hieu van
ve pham » vi pham, v pham, ve phan
van cua » vang cua, ban cua, dan cua
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 ((nang ma) OR (nang cao)) hoi. hieu ve pham duc va doanh van cua te~.
• Adding a wildcard symbol may retrieve word variants: tu sach ky ((nang ma) or (nang cao)) hoi. hieu ve pham duc va doanh van cua te*.