Perhaps you should try some spelling variations:
toc cach » hoc cach, toc sach, truoc cach
cach tu » cach thuc
tu nang » tru nang, tu nong, tu nano
cam duc » cam xuc, cao duc, pham duc
va dinh » van dinh, va kinh, va tinh
x hoi » xa hoi, o hoi, x ho
de va » de van, ke va, le va
te va » tu va
thiet » thieu

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

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