Perhaps you should try some spelling variations:
thieu nien » thien nhien
hieu vien » hieu hien, hieu viec, hieu tieng
hanh vai » hanh vi, hanh va, hanh tai
vai cua » dai cua, hai cua, lai cua
su sach » so sach, vu sach
sach ty » sach y, sach tu, sach thu
cua tre » cua te, cuu tre, cua triet
xuc va » duc va, luc va, xac va
tuc va » thuc va, truc va, tuc xa
ang xa » lang xa, mang xa, dang xay
ty ang » ty xang, ty hang, ty anh

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

• Performing a fuzzy search may retrieve terms with similar spellings: su sach ty ang xa hoi. ((hieu vien) OR (thieu nien)) cac ((xuc va) or (tuc va)) hanh vai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ty ang xa hoi. ((hieu vien) OR (thieu nien)) cac ((xuc va) OR (tuc va)) hanh vai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ty ang xa hoi. ((hieu vien) OR (thieu nien)) cac ((xuc va) or (tuc va)) hanh vai cua tre".
• Adding a wildcard symbol may retrieve word variants: su sach ty ang xa hoi. ((hieu vien) OR (thieu nien)) cac ((xuc va) or (tuc va)) hanh vai cua tre*.