Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
hieu van » hieu va, thien van, lieu va
may tich » may tinh, mat tich, mach tich
so sach » so sanh, bo sach, co sach
nang xa » nang x, lang xa, nang ma
hieu ve » hieu va
xuc may » xuc hay, truc may, phuc may
cua tre » cua te, cuu tre, cua triet
va cua » va chua, via cua, ca cua

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

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