Perhaps you should try some spelling variations:
sach thu » sach thue, sach tham, cach thuc
tai cua » thai cua, tai cuc, tri cua
han tai » hang tai, nhan tai, van tai
va cham » va chat, va tham
hieu va » lieu va, hieu qua
cua tuc » cua duc, cua tu, cua thuoc
nang o » nang co, nang ho, nang ro
luc va » tuc va, loc va
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: te ((sach thu) OR (sach thieu)) nang o hoi. hieu va cham ((luc va) OR (duc va)) han tai cua tuc~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te ((sach thu) OR (sach thieu)) nang o hoi. hieu va cham ((luc va) or (duc va)) han tai cua tuc~".
• Adding a wildcard symbol may retrieve word variants: te ((sach thu) OR (sach thieu)) nang o hoi. hieu va cham ((luc va) or (duc va)) han tai cua tuc*.