Perhaps you should try some spelling variations:
hay dong » ha dong, huy dong, hay song
day dong » dao dong, dan dong, dam dong
chua tre » chua tri, cua tre, chua trieu
so sach » so sanh, bo sach, co sach
hieu va » lieu va, hieu qua
vi chua » va chua, vi khuan, chi chua
va lam » van lam, va lap
xuc va » tuc va, luc va, xac va

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 ((hay dong) OR (day dong)) xa hoi. hieu va lam ((xuc va) or (duc va)) hanh vi chua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach ((hay dong) OR (day dong)) xa hoi. hieu va lam ((xuc va) OR (duc va)) hanh vi chua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sach ((hay dong) OR (day dong)) xa hoi. hieu va lam ((xuc va) or (duc va)) hanh vi chua tre".
• Adding a wildcard symbol may retrieve word variants: so sach ((hay dong) OR (day dong)) xa hoi. hieu va lam ((xuc va) or (duc va)) hanh vi chua tre*.