Perhaps you should try some spelling variations:
doc sach » hoc sach, toc sach, nuoc sach
sach thu » sach thue, sach thieu, sach tham
thu nang » thi nang, thu hang, thu bang
hieu va » lieu va, hieu qua
cac luc » cau luc, coc luc, cac nuoc
va hanh » van hanh, va thanh, va danh
lai cua » dai cua, lai chau, thai cua
hai cua » thai cua, dai cua, hoi cua
luc va » duc va, tuc va, loc va
x hoi » xa hoi, o hoi, x ho

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

• Performing a fuzzy search may retrieve terms with similar spellings: doc sach thu nang x hoi. hieu va cac luc va hanh ((lai cua) or (hai cua)) tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc sach thu nang x hoi. hieu va cac luc va hanh ((lai cua) OR (hai cua)) tre.
• Adding a wildcard symbol may retrieve word variants: doc sach thu nang x hoi. hieu va cac luc va hanh ((lai cua) or (hai cua)) tre*.