Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
hieu van » hieu va, thien van, lieu va
van cham » van chat, van tham, va cham
cua viet » ca viet, hoa viet, cua vat
vu sach » vu bach, su sach, vu khach
nang xa » nang x, lang xa, nang ma
y nang » ky nang, ly nang, v nang
soc va » hoc va, doc va, goc va
loc va » hoc va, luc va
vi cua » vai cua, di cua

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: ((toc sach) OR (vu sach)) y nang xa hoi. hieu van cham ((soc va) OR (loc va)) hanh vi cua viet~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((toc sach) or (vu sach)) y nang xa hoi. hieu van cham ((soc va) OR (loc va)) hanh vi cua viet~".
• Adding a wildcard symbol may retrieve word variants: ((toc sach) or (vu sach)) y nang xa hoi. hieu van cham ((soc va) OR (loc va)) hanh vi cua viet*.