Perhaps you should try some spelling variations:
dinh viet » ninh viet, danh viet, trinh viet
hieu van » hieu va, thien van, lieu va
can thuc » dan thuc, van thuc, cay thuc
thuc dan » thuc hanh, hoc dan, thuc vat
dan dinh » dang dinh, doan dinh, van dinh
viet cua » viec cua, viet ca, viet qua
so sach » so sanh, bo sach, co sach
nang xa » nang x, lang xa, mang xa
nang ma » tang ma, sang ma, nang cao
van can » van canh, van ban, ban can
cua tre » cua te, cuu tre, cua triet

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

• Performing a fuzzy search may retrieve terms with similar spellings: so sach y ((nang xa) or (nang ma)) hoi. hieu van can thuc dan dinh viet cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach y ((nang xa) OR (nang ma)) hoi. hieu van can thuc dan dinh viet cua tre.
• Adding a wildcard symbol may retrieve word variants: so sach y ((nang xa) or (nang ma)) hoi. hieu van can thuc dan dinh viet cua tre*.