Perhaps you should try some spelling variations:
hoc sach » hoc sinh, hoc cac, hoc anh
hieu van » hieu va, thien van, lieu va
tinh vai » tinh va, tinh hai, tinh bai
vai cua » dai cua, hai cua, lai cua
va tinh » may tinh
cua tre » cua te, cuu tre, cua triet
hieu ve » hieu va
ty hang » ly hang, thi hang, thu hang
xuc va » duc va, tuc va, luc va

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: hoc sach ((ty xang) or (ty hang)) xa hoi. ((hieu ve) OR (hieu van)) cam xuc va tinh vai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc sach ((ty xang) OR (ty hang)) xa hoi. ((hieu ve) OR (hieu van)) cam xuc va tinh vai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc sach ((ty xang) or (ty hang)) xa hoi. ((hieu ve) OR (hieu van)) cam xuc va tinh vai cua tre".
• Adding a wildcard symbol may retrieve word variants: hoc sach ((ty xang) or (ty hang)) xa hoi. ((hieu ve) OR (hieu van)) cam xuc va tinh vai cua tre*.