Perhaps you should try some spelling variations:
ban doanh » van doanh, san doanh, ban danh
doanh vi » doanh va, doan vi, doanh vien
tu sach » thu sach, su sach, te sach
cuu ban » cuu van, cua ban, cuu san
ve cham » va cham, ve chat, vu cham
sach ky » sac ky, sach y, sach ty
van hoi » van hoc, van hoe, van loi
ky lang » ky nang, ky dang, ky tang
cua tre » cua te, cuu tre, cua triet
vi cua » vai cua, di cua

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 lang ((van hoi) or (van hoa)). hieu ((ve cham) or (va cac)) cuu ban doanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky lang ((van hoi) OR (van hoa)). hieu ((ve cham) OR (va cac)) cuu ban doanh vi cua tre.
• Adding a wildcard symbol may retrieve word variants: tu sach ky lang ((van hoi) or (van hoa)). hieu ((ve cham) or (va cac)) cuu ban doanh vi cua tre*.