Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
va triet » va thiet, va trien, ve triet
nang ma » tang ma, sang ma, nang cao
vu nang » vuc nang, va nang, vu dang
hieu va » hieu qua
sach vu » sach va, sach tu, sach uu
cam duc » cam xuc, cao duc, pham duc
hanh di » hanh vi, hanh de, danh di
hang di » hang doi, hang vi, hang dien
ma hoi » mai hoi, xa hoi, ma hoa

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 vu nang ma hoi. ((hieu va) or (lieu va)) cam duc va ((hanh di) or (hang di)) va triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach vu nang ma hoi. ((hieu va) OR (lieu va)) cam duc va ((hanh di) OR (hang di)) va triet.
• Adding a wildcard symbol may retrieve word variants: toc sach vu nang ma hoi. ((hieu va) or (lieu va)) cam duc va ((hanh di) or (hang di)) va triet*.