Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
nay thuc » nam thuc, cay thuc, day thuc
hai cuu » hai cua, hai chu, hai cuc
dau hai » dai hai, dau ha, cau hai
thuc va » thuc vat, thuc dan, thuc day
hieu va » lieu va, hieu qua
cuu tre » cua tre, cau tren, cau treo
dang ha » dong ha, dung ha, lang ha
dang xa » dang xay, lang xa, dang va
va nay » va ngay, va cay
va dau » va dao

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((toc sach) or (hoc sinh)) ky ((dang xa) OR (dang ha)) hoi. hieu va nay thuc va dau hai cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((toc sach) OR (hoc sinh)) ky ((dang xa) OR (dang ha)) hoi. hieu va nay thuc va dau hai cuu tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((toc sach) or (hoc sinh)) ky ((dang xa) OR (dang ha)) hoi. hieu va nay thuc va dau hai cuu tre".
• Adding a wildcard symbol may retrieve word variants: ((toc sach) or (hoc sinh)) ky ((dang xa) OR (dang ha)) hoi. hieu va nay thuc va dau hai cuu tre*.