Perhaps you should try some spelling variations:
hieu vien » hieu hien, hieu viec, thieu nien
dieu hien » dieu khien, dieu kien, bieu hien
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
cac tac » cac toc, cac bac, cac dac
va hanh » van hanh, va thanh, va danh
cua tre » cua te, cuu tre, cua triet
tac va » tac da, tac xa, tuc va
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.

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach ky nang x hoi. ((hieu vien) or (dieu hien)) cac tac va hanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang x hoi. ((hieu vien) OR (dieu hien)) cac tac va hanh vi cua tre.
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang x hoi. ((hieu vien) or (dieu hien)) cac tac va hanh vi cua tre*.