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

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 tan hanh ki su triet~.
• 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 tan hanh ki su triet*.