Perhaps you should try some spelling variations:
hoc sach » hoc sinh, hoc cac, hoc anh
tan hanh » tan thanh, tang hanh, toan hanh
hieu ve » hieu va, hieu van
cac duc » cac du, cao duc, cac dac
su tien » su kien, su hien, tu tieng
v nang » va nang, vu nang, van nang
ve cac » va cac, vien cac
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.

• If you are trying to use Boolean operators, they must be ALL CAPS: hoc sach ((v nang) OR (cam nang)) x hoi. hieu ve cac duc tan hanh vi su tien~.
• Adding a wildcard symbol may retrieve word variants: hoc sach ((v nang) or (cam nang)) x hoi. hieu ve cac duc tan hanh vi su tien*.