Perhaps you should try some spelling variations:
van thanh » ban thanh, van tuan
toc sach » hoc sach, doc sach, thuoc sach
thanh vi » hanh vi, thanh va, thanh ve
cac nuoc » cap nuoc, dat nuoc, cua nuoc
hieu ve » hieu va, hieu van
cua tre » cua te, cuu tre, cua triet
lang ha » long ha
nang ma » tang ma, sang ma, nang cao
vi cua » vai cua, di cua

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

• Performing a fuzzy search may retrieve terms with similar spellings: toc sach y ((nang ma) or (lang ha)) hoi. hieu ve ((cac nuoc) or (hoc nuoc)) van thanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach y ((nang ma) OR (lang ha)) hoi. hieu ve ((cac nuoc) OR (hoc nuoc)) van thanh vi cua tre.
• Adding a wildcard symbol may retrieve word variants: toc sach y ((nang ma) or (lang ha)) hoi. hieu ve ((cac nuoc) or (hoc nuoc)) van thanh vi cua tre*.