Perhaps you should try some spelling variations:
hieu vien » hieu hien, hieu viec, thieu nien
vien cac » vien bach, vien dai, vien da
hanh lai » hanh lam, hanh tai, thanh lap
lai cua » dai cua, hai cua, lai chau
sach ky » sac ky, sach y, sach ty
tu sach » thu sach, su sach, te sach
ky sang » ky nang, ky dang, ky tang
cua tre » cua te, cuu tre, cua triet
xuc va » duc va, tuc va, xac va
luc va » duc va, tuc va, loc va
ma hoi » mai hoi, ma hoa, me hoi

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 sang ((ma hoi) or (xa hoi)). hieu vien cac ((xuc va) OR (luc va)) hanh lai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky sang ((ma hoi) OR (xa hoi)). hieu vien cac ((xuc va) OR (luc va)) hanh lai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky sang ((ma hoi) or (xa hoi)). hieu vien cac ((xuc va) OR (luc va)) hanh lai cua tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ky sang ((ma hoi) or (xa hoi)). hieu vien cac ((xuc va) OR (luc va)) hanh lai cua tre*.