Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
hieu van » hieu va, thien van, lieu va
banh vi » hanh vi, ban vi, benh vi
cuc ban » cua ban, cac ban, cuu ban
duc ban » duc tan, duc van, dua ban
mang xa » lang xa, mang may, dang xay
ty mang » ty xang, ty hang, tin mang
vu sach » vu bach, su sach, vu khach
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: ((thu sach) or (vu sach)) ty mang xa hoi. hieu van nam ((duc ban) or (cuc ban)) banh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((thu sach) OR (vu sach)) ty mang xa hoi. hieu van nam ((duc ban) OR (cuc ban)) banh vi cua tre.
• Adding a wildcard symbol may retrieve word variants: ((thu sach) or (vu sach)) ty mang xa hoi. hieu van nam ((duc ban) or (cuc ban)) banh vi cua tre*.