Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
cam truc » cau truc, nam truc, lam truoc
dinh thi » dinh tri
danh tai » doanh tai, dinh tai, hanh tai
hieu van » hieu va, thien van, lieu va
truc va » thuc va, thuc vat, trung va
van cam » van nam, van lam, van cau
cuc tre » duc tre, cua tre, cuu tre
y nang » ky nang, ly nang, v nang
o hoi » co hoi, o hoc, o hai
x hoi » xa hoi, x ho, 5 hoi

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 y nang ((x hoi) OR (o hoi)). hieu van cam truc va ((danh tai) OR (dinh thi)) cuc tre~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sach y nang ((x hoi) OR (o hoi)). hieu van cam truc va ((danh tai) or (dinh thi)) cuc tre~".
• Adding a wildcard symbol may retrieve word variants: thu sach y nang ((x hoi) OR (o hoi)). hieu van cam truc va ((danh tai) or (dinh thi)) cuc tre*.