Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
hieu cua » hieu qua, dieu cua, bieu cua
cac thu » cach thuc, cac thoi
ty mang » ty xang, ty hang, tin mang
mang xa » lang xa, mang may, dang xay
van anh » van thanh, tuan anh, van minh
vi cua » vai cua, di cua
anh vi » hanh vi, anh va, anh ve
cac tu » cach tu, cac du, tac tu
cua te » cua tu

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((te sach) or (toc sach)) ty mang xa hoi. hieu cua ((cac tu) OR (cac thu)) van anh vi cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((te sach) OR (toc sach)) ty mang xa hoi. hieu cua ((cac tu) OR (cac thu)) van anh vi cua te*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((te sach) or (toc sach)) ty mang xa hoi. hieu cua ((cac tu) OR (cac thu)) van anh vi cua te*".