Perhaps you should try some spelling variations:
hieu vien » hieu hien, hieu viec, thieu nien
vien cac » vien bach, vien dai, vien da
hanh vai » hanh vi, hanh va, hanh tai
vai cua » dai cua, hai cua, lai cua
su sach » so sach, vu sach
cua tre » cua te, cuu tre, cua triet
ty anh » ly anh, thuy anh
xuc va » duc va, luc va, xac va
tuc va » thuc va, truc va, tuc xa
ty ang » ty xang, ty hang

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) OR (ty anh)) xa hoi. hieu vien 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) OR (ty anh)) xa hoi. hieu vien 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) OR (ty anh)) xa hoi. hieu vien cac ((xuc va) or (tuc va)) hanh vai cua tre".
• Adding a wildcard symbol may retrieve word variants: su sach ((ty ang) OR (ty anh)) xa hoi. hieu vien cac ((xuc va) or (tuc va)) hanh vai cua tre*.