Perhaps you should try some spelling variations:
hac thuc » hoc thuc, ha thuc, thach thuc
hieu van » hieu va, thien van, lieu va
bo sach » co sach, hoc sach
va hanh » van hanh, va thanh, va danh
thuc va » thuc vat, thuc dan, thuc day
van hac » van hoc, van ha, van hai
cua tre » cua te, cuu tre, cua triet
sang ma » tang ma, sang tao, mang may
nang ma » tang ma, nang cao, mang may
vi cua » vai cua, di cua

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: bo sach y ((nang x) OR (((nang ma) OR (sang ma)))) hoi. hieu van hac thuc va hanh vi cua tre~.
• Adding a wildcard symbol may retrieve word variants: bo sach y ((nang x) or (((nang ma) or (sang ma)))) hoi. hieu van hac thuc va hanh vi cua tre*.