Perhaps you should try some spelling variations:
toc sach » doc sach, thuoc sach, nuoc sach
hoc sach » hoc sinh, hoc cac, hoc anh
nay thuc » nam thuc, cay thuc, day thuc
dao vai » dao van, dao bai, dao hai
thuc va » thuc vat, thuc dan, thuc day
hieu va » lieu va, hieu qua
cuu tre » cua tre, cau tren, cau treo
dang xa » dang xay, lang xa, dang ha
ky dang » ky nang, ky danh
dao va » dao van, tao va, do va
va nay » va ngay, va cay

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 sach)) ky dang xa hoi. hieu va nay thuc va ((dao vai) OR (dao va)) cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((toc sach) OR (hoc sach)) ky dang xa hoi. hieu va nay thuc va ((dao vai) OR (dao va)) cuu tre*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((toc sach) or (hoc sach)) ky dang xa hoi. hieu va nay thuc va ((dao vai) OR (dao va)) cuu tre*".