Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
su sach » so sach, vu sach
cua tre » cua te, cua triet, dua tren
cuu tre » cau tren, cau treo
van cac » van hac, van cau, van bac
nang xa » nang x, lang xa, nang ma
toc va » hoc va, tuc va, loc va
y nang » ky nang, ly nang, v nang
toc ta » toc tay, toc thai

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 y nang xa hoi. hieu van cac ((toc va) OR (toc ta)) hanh vi ((cua tre) or (cuu tre))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach y nang xa hoi. hieu van cac ((toc va) OR (toc ta)) hanh vi ((cua tre) OR (cuu tre)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach y nang xa hoi. hieu van cac ((toc va) OR (toc ta)) hanh vi ((cua tre) or (cuu tre))".
• Adding a wildcard symbol may retrieve word variants: su sach y nang xa hoi. hieu van cac ((toc va) OR (toc ta)) hanh vi ((cua tre) or (cuu tre))*.