Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
hieu ve » hieu va, hieu van
su tien » su kien, su hien, tu tieng
v nang » va nang, vu nang, van nang
ve cac » va cac, vien cac
va anh » van anh, va danh, va hanh
anh ki » anh kinh, anh kiem, anh kien
x hoi » xa hoi, o hoi, x ho
du va » dau va, tu va, su va
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: toc sach ((v nang) or (cam nang)) x hoi. hieu ve cac du va anh ki su tien~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ((v nang) OR (cam nang)) x hoi. hieu ve cac du va anh ki su tien*.