Perhaps you should try some spelling variations:
cau thuc » cau truc, cuu thuc, can thuc
hoc sach » hoc sinh, hoc cac, hoc anh
hieu van » hieu va, thien van, lieu va
su sach » so sach, vu sach
lai cua » dai cua, hai cua, lai chau
va danh » va dinh, va hanh, dia danh
van cau » van dau, van hau, van chat
cua tre » cua te, cuu tre, cua triet
v nang » va nang, vu nang, van nang
va dan » ca dan, va dao, va dau
x hoi » xa hoi, o hoi, x ho

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: ((su sach) OR (hoc sach)) v nang x hoi. hieu van cau thuc ((va danh) OR (va dan)) lai cua tre~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((su sach) or (hoc sach)) v nang x hoi. hieu van cau thuc ((va danh) OR (va dan)) lai cua tre~".
• Adding a wildcard symbol may retrieve word variants: ((su sach) or (hoc sach)) v nang x hoi. hieu van cau thuc ((va danh) OR (va dan)) lai cua tre*.