Perhaps you should try some spelling variations:
thuoc sach » hoc sach, nuoc sach, thuat sach
thanh giau » thanh gian, thanh giang, thanh lieu
hieu van » hieu va, thien van, lieu va
giau cua » gian cua, gia cua, dieu cua
sach ky » sac ky, sach y, sach ty
van cac » van hac, van cau, van bac
cua tre » cua te, cuu tre, cua triet
do van » dao van, so van
x hoi » xa hoi, x ho, 5 hoi
o hoi » co hoi, o hoc, o hai

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

• Performing a fuzzy search may retrieve terms with similar spellings: thuoc sach ky nang ((x hoi) OR (o hoi)). hieu van cac ((do van) or (vo van)) thanh giau cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thuoc sach ky nang ((x hoi) OR (o hoi)). hieu van cac ((do van) OR (vo van)) thanh giau cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thuoc sach ky nang ((x hoi) OR (o hoi)). hieu van cac ((do van) or (vo van)) thanh giau cua tre".
• Adding a wildcard symbol may retrieve word variants: thuoc sach ky nang ((x hoi) OR (o hoi)). hieu van cac ((do van) or (vo van)) thanh giau cua tre*.