Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
van dinh » van minh, van dich, va dinh
hieu va » lieu va, hieu qua
ca viet » va viet, co viet, hoa viet
va cao » va cac, va co, va dao
cao tu » cao thu, co tu, cao su
tu van » tu va
van ca » van cau, van cua, dan ca
x hoi » xa hoi, o hoi, x ho

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((te sach) OR (toc sach)) ky nang x hoi. hieu va cao tu van dinh van ca viet~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((te sach) OR (toc sach)) ky nang x hoi. hieu va cao tu van dinh van ca viet".
• Adding a wildcard symbol may retrieve word variants: ((te sach) OR (toc sach)) ky nang x hoi. hieu va cao tu van dinh van ca viet*.