Perhaps you should try some spelling variations:
van dinh » van minh, va dinh, xuan dinh
su triet » su viet, su tien, ve triet
te sach » toc sach
hieu va » lieu va, hieu qua
y nang » ky nang, ly nang, v nang
ro hai » co hai, o hai, do hai
so hai » son hai, su hai, so ha
vai su » va su, van su, lai su
va am » va lam, va cam

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

• If you are trying to use Boolean operators, they must be ALL CAPS: te sach y nang ((ro hai) OR (so hai)). hieu va am thuc ((van dinh) OR (van dich)) vai su triet~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach y nang ((ro hai) or (so hai)). hieu va am thuc ((van dinh) OR (van dich)) vai su triet~".
• Adding a wildcard symbol may retrieve word variants: te sach y nang ((ro hai) or (so hai)). hieu va am thuc ((van dinh) OR (van dich)) vai su triet*.