Perhaps you should try some spelling variations:
thuat sach » thuat lanh, thuat san
sach ty » sach y, sach tu, sach thu
ty nang » ky nang, ty xang, ty hang
dao cua » dai cua, day cua, dan cua
cua tre » cua te, cuu tre, cua triet
va dat » va dao, va dap, va dai
va dau » va dao
x hoi » xa hoi, o hoi, 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: thuat sach ty nang ((x hoi) OR (x ho)). hieu ((va dat) OR (va dau)) nuoc va van dao cua tre~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thuat sach ty nang ((x hoi) or (x ho)). hieu ((va dat) OR (va dau)) nuoc va van dao cua tre~".
• Adding a wildcard symbol may retrieve word variants: thuat sach ty nang ((x hoi) or (x ho)). hieu ((va dat) OR (va dau)) nuoc va van dao cua tre*.