Perhaps you should try some spelling variations:
sach van » sach han, sach va, cach van
bach van » bach dan, cach van, bach dang
hanh ve » hanh vi, hanh va, hanh kem
qua ban » cua ban, qua quan
duc ban » duc tan, duc van, dua ban
hieu ve » hieu va, hieu van
su viet » so viet
ve cac » va cac, vien cac
x hoi » xa hoi, o hoi, x ho
ve su » va su

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

• Performing a fuzzy search may retrieve terms with similar spellings: su ((sach van) OR (bach van)) nang x hoi. hieu ve cac ((duc ban) or (qua ban)) hanh ve su viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su ((sach van) OR (bach van)) nang x hoi. hieu ve cac ((duc ban) OR (qua ban)) hanh ve su viet*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su ((sach van) OR (bach van)) nang x hoi. hieu ve cac ((duc ban) or (qua ban)) hanh ve su viet*".