Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
thanh le » thinh le, thanh ve, thanh de
dang xay » dang van, van xay
van cau » van dau, van hau, van chat
duc ban » duc tan, duc van, dua ban
luc ban » cuc ban, luc bat, luc van
tu sach » thu sach, te sach, tu cach
xay hoi » xa hoi, tay hoi, cay phoi
ky dang » ky nang, ky danh
su sach » so sach, vu sach
cua tre » cua te, cuu tre, cua triet
le cua » ly cua

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((tu sach) or (su sach)) ky dang xay hoi. hieu van cau ((luc ban) OR (duc ban)) thanh le cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (su sach)) ky dang xay hoi. hieu van cau ((luc ban) OR (duc ban)) thanh le cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) or (su sach)) ky dang xay hoi. hieu van cau ((luc ban) OR (duc ban)) thanh le cua tre".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (su sach)) ky dang xay hoi. hieu van cau ((luc ban) OR (duc ban)) thanh le cua tre*.