Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
so sach » so sanh, bo sach, co sach
va hanh » van hanh, va thanh, va danh
cam duc » cam xuc, cao duc, pham duc
hieu ve » hieu va
cua tre » cua te, cuu tre, cua triet
cai hoi » cau hoi, dai hoi, cai hoa
y nang » ky nang, ly nang, may nang
v nang » va nang, vu nang, van nang
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: so sach ((y nang) or (v nang)) cai hoi. ((hieu ve) or (hieu van)) cam duc va hanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach ((y nang) OR (v nang)) cai hoi. ((hieu ve) OR (hieu van)) cam duc va hanh vi cua tre.
• Adding a wildcard symbol may retrieve word variants: so sach ((y nang) or (v nang)) cai hoi. ((hieu ve) or (hieu van)) cam duc va hanh vi cua tre*.