Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
su sach » vu sach
so sach » so sanh, bo sach, co sach
nang xa » nang x, lang xa, nang ma
van cac » van hac, van cau, van bac
cua tre » cua te, cuu tre, cua triet
y nang » ky nang, ly nang, v nang
tuc va » thuc va, truc va, duc va
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: ((su sach) or (so sach)) y nang xa hoi. hieu van cac ((tuc va) OR (tuc xa)) hanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((su sach) OR (so sach)) y nang xa hoi. hieu van cac ((tuc va) OR (tuc xa)) hanh vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((su sach) or (so sach)) y nang xa hoi. hieu van cac ((tuc va) OR (tuc xa)) hanh vi cua tre".
• Adding a wildcard symbol may retrieve word variants: ((su sach) or (so sach)) y nang xa hoi. hieu van cac ((tuc va) OR (tuc xa)) hanh vi cua tre*.