Perhaps you should try some spelling variations:
sach van » sach han, sach va, bach van
van nang » van quang, van ban, van dong
su triet » su viet, ve triet
ban hanh » ban hang
tu sach » thu sach, su sach, te sach
hanh ki » hanh vi, hanh ky, hanh kien
duc ban » duc tan, duc van, dua ban
su tien » su kien, su hien, tu tieng
cac duc » cac du, cao duc, cac dac
hieu ve » hieu va, hieu van
ve cac » va cac, vien cac
o hoi » co hoi, o hoc, o hai
x hoi » xa hoi, x ho, 5 hoi

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