Perhaps you should try some spelling variations:
thuoc sach » hoc sach, nuoc sach, thuat sach
toc sach » hoc sach, doc sach, nuoc sach
thuc dan » thuc hanh, hoc dan, thuc vat
dan dan » dang dan, ban dan, dao dan
hieu va » hieu qua
lang xa » lang ha, dang xay, lang van
ky lang » ky nang, ky dang, ky tang
cuu tre » cua tre, cau tren, cau treo
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 (thuoc sach)) ky lang xa hoi. ((hieu va) OR (lieu va)) am thuc dan dan va cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((toc sach) OR (thuoc sach)) ky lang xa hoi. ((hieu va) OR (lieu va)) am thuc dan dan va cuu tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((toc sach) or (thuoc sach)) ky lang xa hoi. ((hieu va) OR (lieu va)) am thuc dan dan va cuu tre".
• Adding a wildcard symbol may retrieve word variants: ((toc sach) or (thuoc sach)) ky lang xa hoi. ((hieu va) OR (lieu va)) am thuc dan dan va cuu tre*.