Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
nang xa » nang x, lang xa, nang ma
hieu va » hieu qua
cao duc » dao duc, cao suc, giao duc
va hanh » van hanh, va thanh, va danh
sach v » sach va, sach y, sach 2
v nang » va nang, vu nang, van nang
de va » de van, ke va, le va
te va » tu va

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: toc sach v nang xa hoi. ((hieu va) or (lieu va)) cao duc va hanh ((de va) OR (te va)) triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach v nang xa hoi. ((hieu va) OR (lieu va)) cao duc va hanh ((de va) OR (te va)) triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach v nang xa hoi. ((hieu va) or (lieu va)) cao duc va hanh ((de va) OR (te va)) triet".
• Adding a wildcard symbol may retrieve word variants: toc sach v nang xa hoi. ((hieu va) or (lieu va)) cao duc va hanh ((de va) OR (te va)) triet*.