Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
sach van » sach han, sach va, bach van
van nang » van quang, van ban, van dong
nang xa » nang x, lang xa, nang ma
hieu va » lieu va, hieu qua
dua ban » dia ban, cua ban, qua ban
hanh va » hang va, hanh vi
su viet » so viet

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 van nang xa hoi. hieu va cac ((duc tan) or (dua ban)) hanh va su viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach van nang xa hoi. hieu va cac ((duc tan) OR (dua ban)) hanh va su viet*.