Perhaps you should try some spelling variations:
dieu hien » dieu khien, dieu kien, bieu hien
hieu vien » hieu viec, thieu nien, hieu tieng
hieu hien » bieu hien, chieu chien, dieu khien
tu sach » thu sach, su sach, te sach
va hanh » van hanh, va thanh, va danh
cac dac » cac dan, cac dai, cac bac
cua tre » cua te, cuu tre, cua triet
sach ky » sac ky, sach y, sach ty
dac va » duc va, day va, dat 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 (((hieu hien) OR (dieu hien)))) cac dac 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 (((hieu hien) OR (dieu hien)))) cac dac va hanh vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky nang x hoi. ((hieu vien) or (((hieu hien) OR (dieu hien)))) cac dac va hanh vi cua tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang x hoi. ((hieu vien) or (((hieu hien) OR (dieu hien)))) cac dac va hanh vi cua tre*.