Perhaps you should try some spelling variations:
doc sach » hoc sach, toc sach, nuoc sach
dang xay » dang van, van xay
va hanh » van hanh, va thanh, va danh
van cam » van lam, van cau, van dam
te sach » toc sach
xay hoi » xa hoi, tay hoi, cay phoi
ty dang » ty xang, ky dang, ty hang
cua tre » cua te, cuu tre, cua triet
luc va » duc va, tuc va, loc va
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: ((te sach) or (doc sach)) ty dang xay hoi. hieu ((van cam) OR (van nam)) luc va hanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((te sach) OR (doc sach)) ty dang xay hoi. hieu ((van cam) OR (van nam)) luc va hanh vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((te sach) or (doc sach)) ty dang xay hoi. hieu ((van cam) OR (van nam)) luc va hanh vi cua tre".
• Adding a wildcard symbol may retrieve word variants: ((te sach) or (doc sach)) ty dang xay hoi. hieu ((van cam) OR (van nam)) luc va hanh vi cua tre*.