Perhaps you should try some spelling variations:
toc sach » doc sach, thuoc sach, nuoc sach
hoc sach » hoc sinh, hoc cac, hoc anh
nam thuc » nam thuoc, am thuc, nam thu
thuc va » thuc vat, thuc dan, thuc day
hieu va » hieu qua
cuu tre » cua tre, cau tren, cau treo
lang xa » lang ha, dang xay, lang van
ky lang » ky nang, ky dang, ky tang
va dan » ca dan, va dao, va dau
dan va » doan va, dan ca, ban va
va cuu » va cau, va chu, va huu

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 lang xa hoi. ((hieu va) or (lieu va)) nam thuc va dan va cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((toc sach) OR (hoc sach)) ky lang xa hoi. ((hieu va) OR (lieu va)) nam thuc va dan va cuu tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((toc sach) OR (hoc sach)) ky lang xa hoi. ((hieu va) or (lieu va)) nam thuc va dan va cuu tre".
• Adding a wildcard symbol may retrieve word variants: ((toc sach) OR (hoc sach)) ky lang xa hoi. ((hieu va) or (lieu va)) nam thuc va dan va cuu tre*.