Perhaps you should try some spelling variations:
van doanh » toan doanh, van dong, van thanh
thu sach » tu sach, thuat sach, thuoc sach
kho tang » cao tang
hieu cac » hieu va, hieu van, dieu can
sach kho » bach khoa, sach dao, sach nha
hieu luc » hieu luat, hieu qua
tang ma » mang may, tang van
dan cua » ban cua, dai cua, day cua
toc van » hoc van, toc san, tac van
ma hoi » mai hoi, xa hoi, ma hoa

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: thu sach kho tang ma hoi. dieu ((hieu cac) OR (hieu luc)) toc van doanh ((dan cua) OR (dan ca)) tu~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sach kho tang ma hoi. dieu ((hieu cac) OR (hieu luc)) toc van doanh ((dan cua) or (dan ca)) tu~".
• Adding a wildcard symbol may retrieve word variants: thu sach kho tang ma hoi. dieu ((hieu cac) OR (hieu luc)) toc van doanh ((dan cua) or (dan ca)) tu*.