Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
van cham » van chat, van tham, va cham
hieu van » hieu va, thien van, lieu va
cua viet » ca viet, hoa viet, cua vat
vu sach » vu bach, su sach, vu khach
nang xa » nang x, lang xa, mang xa
va hanh » van hanh, va thanh, va danh
nang ma » tang ma, sang ma, nang cao
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: ((toc sach) OR (vu sach)) y ((nang xa) OR (nang ma)) hoi. hieu van cham soc 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) OR (nang ma)) hoi. hieu van cham soc va hanh vi cua viet~".
• Adding a wildcard symbol may retrieve word variants: ((toc sach) or (vu sach)) y ((nang xa) OR (nang ma)) hoi. hieu van cham soc va hanh vi cua viet*.