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
su sach » so sach, vu sach
nang xa » nang x, lang xa, nang ma
va hanh » van hanh, va thanh, va danh
y nang » ky nang, ly nang, v nang
soc va » hoc va, loc va, doc 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: ((((te sach) OR (toc sach))) OR (su sach)) y nang xa hoi. hieu van cham soc va hanh vi cua viet~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((((te sach) OR (toc sach))) or (su sach)) y nang xa hoi. hieu van cham soc va hanh vi cua viet~".
• Adding a wildcard symbol may retrieve word variants: ((((te sach) OR (toc sach))) or (su sach)) y nang xa hoi. hieu van cham soc va hanh vi cua viet*.