Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
va tuyen » va truyen, tac tuyen, ke tuyen
va nang » van nang, da nang, cam nang
hieu va » hieu qua
cam duc » cam xuc, cao duc, pham duc
va hanh » van hanh, va thanh, va danh
v nang » vu nang, van nang, voi nang
kem va » kiem va, kiem van

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