Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
hieu van » hieu va, thien van, lieu va
hieu ve » hieu va
sach va » sach xa, sach ha, sach dao
duc van » duc va, duc tan, duc manh
dua ban » dia ban, cua ban, qua ban
va nang » van nang, da nang, cam nang
su viet » so viet
x hoi » xa hoi, o hoi, x ho
vi su » va su, ve su, ki su

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 va nang x hoi. ((hieu ve) OR (hieu van)) cac ((duc van) or (dua ban)) hanh vi su viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach va nang x hoi. ((hieu ve) OR (hieu van)) cac ((duc van) OR (dua ban)) hanh vi su viet*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sach va nang x hoi. ((hieu ve) OR (hieu van)) cac ((duc van) or (dua ban)) hanh vi su viet*".