Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
te sach » toc sach
vai cua » dai cua, hai cua, lai cua
dau vai » dau va, dau hai, dau tai
cao duc » dao duc, cao suc, giao duc
cam duc » cam xuc, pham duc, nam duoc
ky dang » ky nang, ky danh
ky lang » ky nang, ky tang, tay lang
cua tre » cua te, cuu tre, cua triet
va dau » va dao

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

• Performing a fuzzy search may retrieve terms with similar spellings: te sach ((ky lang) or (ky dang)) xa hoi. hieu van ((cam duc) or (cao duc)) va dau vai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach ((ky lang) OR (ky dang)) xa hoi. hieu van ((cam duc) OR (cao duc)) va dau vai cua tre.
• Adding a wildcard symbol may retrieve word variants: te sach ((ky lang) or (ky dang)) xa hoi. hieu van ((cam duc) or (cao duc)) va dau vai cua tre*.