Perhaps you should try some spelling variations:
hieu vien » hieu hien, hieu viec, thieu nien
hanh vai » hanh vi, hanh va, hanh tai
vien cac » vien bach, vien dai, vien da
su sach » so sach, vu sach
sach ty » sach y, sach tu, sach thu
vai cua » dai cua, hai cua, lai cua
cua tre » cua te, cuu tre, cua triet
hang xa » hoang xa, hang va, hang ca
ty hang » ly hang, ty xang, thi hang
xac va » tac va, ac va, mac va
bac va » ban va, bac ha, bao va
tuc va » thuc va, truc va, tuc xa

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 hang xa hoi. hieu vien cac ((((xac va) or (bac va))) or (tuc va)) hanh vai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ty hang xa hoi. hieu vien cac ((((xac va) OR (bac va))) OR (tuc va)) hanh vai cua tre.
• Adding a wildcard symbol may retrieve word variants: su sach ty hang xa hoi. hieu vien cac ((((xac va) or (bac va))) or (tuc va)) hanh vai cua tre*.