Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
cau viet » ca viet, chu viet, cao viet
hieu va » lieu va, hieu qua
va dinh » van dinh, va kinh, va tinh
van cau » van dau, van hau, van chat
va cao » va cac, va co, va dao
cao tu » cao thu, co tu, cao su
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 va dinh van cau 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 va dinh van cau viet".
• Adding a wildcard symbol may retrieve word variants: ((te sach) OR (toc sach)) ky nang x hoi. hieu va cao tu va dinh van cau viet*.