Perhaps you should try some spelling variations:
hieu van » thien van, lieu va, hieu ve
nang cai » nang cao, nang tai, nang cap
hanh vai » hanh vi, hanh tai, hanh van
so sach » so sanh, bo sach, co sach
hanh va » hang va, hanh vi
sach ky » sac ky, sach y, sach ty
cai hoi » cau hoi, dai hoi, cai hoa
hieu va » lieu va, hieu qua
cua tre » cua te, cuu tre, cua triet
xuc va » duc va, tuc va, luc va

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

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