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
hai cua » thai cua, dai cua, hoi cua
lai cua » dai cua, lai chau, thai cua
va danh » va dinh, va dan, dia danh
va hanh » van hanh, va thanh, ban hanh
cac luc » cau luc, coc luc, cac nuoc
hieu va » lieu va, hieu qua
nang xa » nang x, lang xa, nang ma

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 xa hoi. hieu va cac luc ((va hanh) OR (va danh)) ((lai cua) or (hai cua)) tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc sach thu nang xa hoi. hieu va cac luc ((va hanh) OR (va danh)) ((lai cua) OR (hai cua)) tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "doc sach thu nang xa hoi. hieu va cac luc ((va hanh) OR (va danh)) ((lai cua) or (hai cua)) tre".
• Adding a wildcard symbol may retrieve word variants: doc sach thu nang xa hoi. hieu va cac luc ((va hanh) OR (va danh)) ((lai cua) or (hai cua)) tre*.