Perhaps you should try some spelling variations:
tu sach » thu sach, su sach, te sach
qua cac » cua cac
dao vai » dao van, dao va, dao bai
vai cua » dai cua, hai cua, lai cua
cua tre » cua te, cuu tre, cua triet
y lang » o lang, tay lang, yen lang
_ lang » o lang, _ land
tuc va » thuc va, truc va, duc va

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 ((y lang) OR (_ lang)) xa hoi. hieu qua cac ((tuc va) or (tuc xa)) dao vai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ((y lang) OR (_ lang)) xa hoi. hieu qua cac ((tuc va) OR (tuc xa)) dao vai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ((y lang) OR (_ lang)) xa hoi. hieu qua cac ((tuc va) or (tuc xa)) dao vai cua tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ((y lang) OR (_ lang)) xa hoi. hieu qua cac ((tuc va) or (tuc xa)) dao vai cua tre*.