Perhaps you should try some spelling variations:
thieu nien » thien nhien
nien day » nien dau, nhien dai, hien dai
van hanh » van thanh, ban hanh, van anh
thuc van » thuc vat, thuc dan, thuc va
day thuc » dan thuc, cay thuc, dai thuc
cua tre » cua te, cua triet, dua tren
su sach » so sach, vu sach
sach ty » sach y, sach tu, sach thu
xang xa » lang xa, mang xa, dang xay
cuu tre » cau tren, cau treo
ang xa » lang xa, mang xa, dang xay

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

• Performing a fuzzy search may retrieve terms with similar spellings: su sach ty ((xang xa) OR (ang xa)) hoi. thieu nien day thuc van hanh vi ((cua tre) or (cuu tre))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ty ((xang xa) OR (ang xa)) hoi. thieu nien day thuc van hanh vi ((cua tre) OR (cuu tre)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ty ((xang xa) OR (ang xa)) hoi. thieu nien day thuc van hanh vi ((cua tre) or (cuu tre))".
• Adding a wildcard symbol may retrieve word variants: su sach ty ((xang xa) OR (ang xa)) hoi. thieu nien day thuc van hanh vi ((cua tre) or (cuu tre))*.