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, vu dinh
va tinh » may tinh
x hoi » xa hoi, o hoi, x ho
de va » de van, te va, ke 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) OR (va tinh)) de 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) OR (va tinh)) de 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) OR (va tinh)) de 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) OR (va tinh)) de va thiet*.