Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
vanh dai » van dai, vanh tai, lanh dao
tu cach » tu cac
hieu va » lieu va, hieu qua
cac luc » cau luc, coc luc, cac nuoc
va vanh » va van, va danh, va hanh
cua tre » cua te, cuu tre, cua triet
luc va » duc va, tuc va, loc va
x hoi » o hoi, x ho, 5 hoi

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

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