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 » hoa viet, cua vat, cua dieu
vu sach » vu bach, su sach, vu khach
nang xa » nang x, lang xa, nang ma
va hanh » van hanh, va thanh, va danh
ca viet » va viet, co viet, hoa viet
y nang » ky nang, ly nang, v nang
soc va » hoc va, loc va, doc va

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 hanh vi ((cua viet) OR (ca 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 hanh vi ((cua viet) OR (ca viet))~".
• Adding a wildcard symbol may retrieve word variants: ((toc sach) or (vu sach)) y nang xa hoi. hieu van cham soc va hanh vi ((cua viet) OR (ca viet))*.