Perhaps you should try some spelling variations:
sach thu » sach thue, sach thieu, sach tham
thu nang » thi nang, thu hang, thu bang
cham luc » nhan luc, cham cuu, chat lua
te sach » toc sach
hieu va » lieu va, hieu qua
van tai » von tai, van tuan
tai cua » thai cua, tai cuc, tri cua
cua duc » cua tuc, cua nuoc, cua quoc
x hoi » xa hoi, o hoi, 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: te sach thu nang ((x hoi) OR (x ho)). hieu va ((cham luc) OR (cham soc)) va van tai cua duc~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach thu nang ((x hoi) or (x ho)). hieu va ((cham luc) OR (cham soc)) va van tai cua duc~".
• Adding a wildcard symbol may retrieve word variants: te sach thu nang ((x hoi) or (x ho)). hieu va ((cham luc) OR (cham soc)) va van tai cua duc*.