Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
tu sach » thu sach, su sach, te sach
ky dang » ky danh
nam tuc » nam thuc, nam truc, nam tu
vai cua » dai cua, hai cua, lai cua
cua tre » cua te, cuu tre, cua triet
va dan » va dao, va dau, va dap
ca dan » cac dan, ca dao

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) or (ky dang)) xa hoi. hieu van nam tuc ((va dan) OR (ca dan)) vai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ((ky nang) OR (ky dang)) xa hoi. hieu van nam tuc ((va dan) OR (ca dan)) vai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ((ky nang) or (ky dang)) xa hoi. hieu van nam tuc ((va dan) OR (ca dan)) vai cua tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ((ky nang) or (ky dang)) xa hoi. hieu van nam tuc ((va dan) OR (ca dan)) vai cua tre*.