Perhaps you should try some spelling variations:
doanh van » doan van, doanh va, doanh ban
toc sach » doc sach, thuoc sach, nuoc sach
hoc sach » hoc sinh, hoc cac, hoc anh
kho tang » cao tang
va doanh » van doanh, vay doanh, va danh
hieu va » lieu va, hieu qua
van cua » vang cua, ban cua, dan cua
cac tuc » cac toc, cac tu, cac tac
cua tre » cua te, cuu tre, cua triet
hieu ve » hieu van
tang ma » mang may, tang van
tuc va » thuc va, truc va, tuc xa

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((toc sach) or (hoc sach)) kho tang ma hoa. ((hieu ve) OR (hieu va)) cac tuc va doanh van cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((toc sach) OR (hoc sach)) kho tang ma hoa. ((hieu ve) OR (hieu va)) cac tuc va doanh van cua tre*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((toc sach) or (hoc sach)) kho tang ma hoa. ((hieu ve) OR (hieu va)) cac tuc va doanh van cua tre*".