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
ty mang » ty xang, tin mang, tri mang
xuc va » duc va, tuc va, luc va
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 mang) OR (ty hang)) xa hoi. hieu ve cac ((xuc va) or (tuc xa)) hanh vai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ((ty mang) OR (ty hang)) xa hoi. hieu ve cac ((xuc va) OR (tuc xa)) hanh vai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ((ty mang) OR (ty hang)) xa hoi. hieu ve cac ((xuc va) or (tuc xa)) hanh vai cua tre".
• Adding a wildcard symbol may retrieve word variants: su sach ((ty mang) OR (ty hang)) xa hoi. hieu ve cac ((xuc va) or (tuc xa)) hanh vai cua tre*.