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
nam thuc » nam thuoc, am thuc, nam thu
dang xay » dang van, van xay
vai cuu » vai cua
dan vai » dan va, dan tai, dan vat
dan dan » dang dan, ban dan, dao dan
hieu va » lieu va, hieu qua
lang xa » lang ha, lang van
cuu tre » cua tre, cau tren, cau treo
va nam » van nam, ha nam, va nay

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