Perhaps you should try some spelling variations:
thuat sach » thuat lanh, thuat san
toc sach » hoc sach, doc sach, thuoc sach
vuc nang » cuc nang, vu nang, chuc nang
cua tre » cua te, cuu tre, cua triet
nang o » nang co, nang ho, nang ro
va cam » va cham, va cao, va cai
luc va » duc va, tuc va, loc va
de cua » le cua, te cua, dieu cua
o hoi » co hoi, o hoc, o hai

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: ((toc sach) or (thuat sach)) vuc nang o hoi. hieu ((va cam) or (va cac)) luc va van de cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((toc sach) OR (thuat sach)) vuc nang o hoi. hieu ((va cam) OR (va cac)) luc va van de cua tre.
• Adding a wildcard symbol may retrieve word variants: ((toc sach) or (thuat sach)) vuc nang o hoi. hieu ((va cam) or (va cac)) luc va van de cua tre*.