Perhaps you should try some spelling variations:
nuoc sach » nguoi sach, hoc sach, cuoc cach
doc sach » hoc sach, toc sach, dac sac
xang xa » lang xa, mang xa, ang xa
hieu va » lieu va, hieu qua
va chat » van chat, va phat, cao chat
xuc van » duc van, luc van, xuc ban
vuc van » duc van, luc van, thuc van
cua tre » cua te, cuu tre, cua triet
vi cua » vai cua, di cua

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) or (nuoc sach)) ty xang xa hoi. hieu va chat ((xuc van) OR (vuc van)) hanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((doc sach) OR (nuoc sach)) ty xang xa hoi. hieu va chat ((xuc van) OR (vuc van)) hanh vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((doc sach) or (nuoc sach)) ty xang xa hoi. hieu va chat ((xuc van) OR (vuc van)) hanh vi cua tre".
• Adding a wildcard symbol may retrieve word variants: ((doc sach) or (nuoc sach)) ty xang xa hoi. hieu va chat ((xuc van) OR (vuc van)) hanh vi cua tre*.