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
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 hoa » voi hoa, va hoa, bi hoa
vi hoc » li hoc, va hoc

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