Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
cau thuc » cau truc, cuu thuc, can thuc
vu sach » vu bach, su sach, vu khach
bo sach » co sach, hoc sach
van cau » van dau, van hau, van chat
thuc va » thuc vat, thuc dan, thuc day
lai cua » hai cua, lai chau, thai cua
y nang » ky nang, ly nang, v nang
va dan » ca dan, va dao, va dau
x hoi » xa hoi, o hoi, x ho

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: ((vu sach) OR (bo sach)) y nang x hoi. hieu van cau thuc va dan ((lai cua) OR (dai cua)) tre~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((vu sach) or (bo sach)) y nang x hoi. hieu van cau thuc va dan ((lai cua) OR (dai cua)) tre~".
• Adding a wildcard symbol may retrieve word variants: ((vu sach) or (bo sach)) y nang x hoi. hieu van cau thuc va dan ((lai cua) OR (dai cua)) tre*.