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

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 cac tuc va ((doanh van) OR (doanh va)) 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 cac tuc va ((doanh van) OR (doanh va)) 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 cac tuc va ((doanh van) OR (doanh va)) cua tre*".