Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
hieu van » thien van, lieu va, hieu ve
van hanh » van thanh, ban hanh, van anh
cua viet » ca viet, hoa viet, cua vat
hieu va » lieu va, hieu qua
va hanh » va thanh, va danh, ban hanh
y nang » ky nang, ly nang, v nang
ve cua » le cua, de cua, te cua

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 y nang x ho. ((hieu van) or (hieu va)) cam xuc ((va hanh) OR (van hanh)) ve cua viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach y nang x ho. ((hieu van) OR (hieu va)) cam xuc ((va hanh) OR (van hanh)) ve cua viet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach y nang x ho. ((hieu van) or (hieu va)) cam xuc ((va hanh) OR (van hanh)) ve cua viet".
• Adding a wildcard symbol may retrieve word variants: toc sach y nang x ho. ((hieu van) or (hieu va)) cam xuc ((va hanh) OR (van hanh)) ve cua viet*.