Perhaps you should try some spelling variations:
thanh hai » thanh phan, thanh hoa, thanh san
van thanh » ban thanh, van tuan
so sach » so sanh, bo sach, co sach
cam duc » cam xuc, cao duc, nam duoc
hai cua » thai cua, dai cua, hoi cua
cua tre » cua te, cuu tre, cua triet
hieu ve » hieu va, hieu van
ky tang » ky dang, kho tang, ky trong
ma hoi » mai hoi, xa hoi, ma hoa

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

• Performing a fuzzy search may retrieve terms with similar spellings: so sach ((ky tang) OR (ky nang)) ma hoi. hieu ve ((cam duc) or (pham duc)) van thanh hai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach ((ky tang) OR (ky nang)) ma hoi. hieu ve ((cam duc) OR (pham duc)) van thanh hai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sach ((ky tang) OR (ky nang)) ma hoi. hieu ve ((cam duc) or (pham duc)) van thanh hai cua tre".
• Adding a wildcard symbol may retrieve word variants: so sach ((ky tang) OR (ky nang)) ma hoi. hieu ve ((cam duc) or (pham duc)) van thanh hai cua tre*.