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

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