Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
sach ky » sac ky, sach y, sach ty
hieu ve » hieu va, hieu van
va doan » va doanh, van doan, va dan
doan vi » doan va, don vi, doan thi
cua tre » cua te, cuu tre, cua triet
cac tu » cac thu, cach tu, tac tu
vi cua » vai cua, di cua
x hoi » xa hoi, o hoi, x ho

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

• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sach ky nang x hoi. hieu ve ((cac tu) OR (cac du)) va doan vi cua tre~".
• Adding a wildcard symbol may retrieve word variants: thu sach ky nang x hoi. hieu ve ((cac tu) OR (cac du)) va doan vi cua tre*.