Perhaps you should try some spelling variations:
toan thanh » tran thanh, hoan thanh, toan thang
thanh vai » thanh hai, thanh van, thanh tai
luc toan » duc toan, quoc toan, luc tai
hieu van » hieu va, thien van, lieu va
tu sach » thu sach, su sach, te sach
vai cua » dai cua, hai cua, lai cua
bao luc » bao thuc
van bao » van ban, van dao
cua tre » cua te, cuu tre, cua triet
sach ky » sac ky, sach y, sach ty
so hoc » co hoc, mo hoc, so hoa
o hoc » co hoc, mo hoc, y hoc
o hoi » co hoi, o hai, o hoa

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 ky nang ((o hoi) or (((o hoc) or (so hoc)))). hieu van bao luc toan thanh vai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang ((o hoi) OR (((o hoc) OR (so hoc)))). hieu van bao luc toan thanh vai cua tre.
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang ((o hoi) or (((o hoc) or (so hoc)))). hieu van bao luc toan thanh vai cua tre*.