Perhaps you should try some spelling variations:
hieu vien » hieu hien, hieu viec, thieu nien
hanh vai » hanh vi, hanh va, hanh tai
sach thu » sach thue, sach thieu, sach tham
dang xay » dang van, van xay
vai cua » dai cua, hai cua, lai cua
vien da » vien dai, hien dai
xay hoi » xa hoi, tay hoi, cay phoi
sach ty » sach y, sach tu, xach tay
cua tre » cua te, cuu tre, cua triet
xac va » tac va, ac va, bac 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) or (sach thu)) dang xay hoi. hieu vien da ((xac va) or (tuc va)) hanh vai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su ((sach ty) OR (sach thu)) dang xay hoi. hieu vien da ((xac va) OR (tuc va)) hanh vai cua tre.
• Adding a wildcard symbol may retrieve word variants: su ((sach ty) or (sach thu)) dang xay hoi. hieu vien da ((xac va) or (tuc va)) hanh vai cua tre*.