Perhaps you should try some spelling variations:
va doanh » van doanh, vay doanh, va danh
te sach » toc sach
sach ky » sac ky, sach y, sach ty
ky dang » ky nang, ky danh
hieu ve » hieu va, hieu van
cac tac » cac toc, cac bac, cac dac
tai cua » thai cua, tai cuc, tri cua
cua tre » cua te, cuu tre, cua triet
ma hoi » mai hoi, ma hoa, me hoi
ve cac » va cac, vien cac
tac va » tac da, tac xa, tuc va

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

• Performing a fuzzy search may retrieve terms with similar spellings: te sach ky dang ((ma hoi) or (xa hoi)). hieu ve cac tac va doanh tai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach ky dang ((ma hoi) OR (xa hoi)). hieu ve cac tac va doanh tai cua tre.
• Adding a wildcard symbol may retrieve word variants: te sach ky dang ((ma hoi) or (xa hoi)). hieu ve cac tac va doanh tai cua tre*.