Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
truc van » truc va, thuc van, truc ban
so sach » bo sach, co sach, hoc sach
so sanh » do sanh
xang xa » lang xa, mang xa, ang xa
van cau » van dau, van hau, van chat
hanh va » hang va, hanh vi
cua tre » cua te, cuu tre, cua triet

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((so sach) OR (so sanh)) ty xang xa hoi. hieu van cau truc van ((dung tai) or (hanh va)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((so sach) OR (so sanh)) ty xang xa hoi. hieu van cau truc van ((dung tai) OR (hanh va)) cua tre*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((so sach) OR (so sanh)) ty xang xa hoi. hieu van cau truc van ((dung tai) or (hanh va)) cua tre*".