Perhaps you should try some spelling variations:
thanh dat » thanh san, thanh hai, thanh van
toc sach » hoc sach, thuoc sach, nuoc sach
doc sach » hoc sach, nuoc sach, dac sac
va thanh » gia thanh, ban thanh, va tinh
hieu van » hieu va, thien van, lieu va
dat cua » dai cua, day cua, mat cua
van cac » van hac, van cau, van bac
mai hoi » mai khoi, dai hoi, lai hoi
cua tre » cua te, cuu tre, cua triet
ma hoi » xa hoi, ma hoa, me hoi
y nang » ky nang, ly nang, v nang
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) OR (doc sach)) y nang ((ma hoi) OR (mai hoi)). hieu van cac du va thanh dat cua tre~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((toc sach) OR (doc sach)) y nang ((ma hoi) or (mai hoi)). hieu van cac du va thanh dat cua tre~".
• Adding a wildcard symbol may retrieve word variants: ((toc sach) OR (doc sach)) y nang ((ma hoi) or (mai hoi)). hieu van cac du va thanh dat cua tre*.