Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
hieu van » hieu va, thien van, lieu va
cac nuoc » cap nuoc, hoc nuoc, dat nuoc
va doanh » van doanh, vay doanh, va danh
doanh vi » doanh va, doan vi, doanh vien
van cac » van hac, van cau, van bac
luy tre » luyen tre
y nang » ky nang, ly nang, v nang
vi luy » vi lua, vi luu
o hoi » co hoi, o hoc, o hai

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 ((5 hoi) OR (o hoi)). hieu van cac nuoc va doanh vi luy tre~.
• Adding a wildcard symbol may retrieve word variants: toc sach y nang ((5 hoi) or (o hoi)). hieu van cac nuoc va doanh vi luy tre*.