Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
va thanh » gia thanh, ban thanh, va tinh
mai hoi » mai khoi, dai hoi, lai hoi
hieu ve » hieu va, hieu van
dat cua » day cua, mat cua, dan cua
y nang » ky nang, ly nang, v nang
ma hoi » xa hoi, ma hoa, me hoi
ve cac » va cac, vien cac
du va » dau va, tu va, su va

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: toc sach y nang ((ma hoi) OR (mai hoi)). hieu ve cac du va thanh ((dat cua) OR (dai cua)) tre~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach y nang ((ma hoi) or (mai hoi)). hieu ve cac du va thanh ((dat cua) OR (dai cua)) tre~".
• Adding a wildcard symbol may retrieve word variants: toc sach y nang ((ma hoi) or (mai hoi)). hieu ve cac du va thanh ((dat cua) OR (dai cua)) tre*.