Perhaps you should try some spelling variations:
thuoc sach » hoc sach, nuoc sach, thuat sach
nam thuc » nam thuoc, am thuc, nam tu
sach nay » sach hay, sach vay, sach nang
vai cuu » vai cua
dan vai » dan va, dan tai, dan vat
hieu va » lieu va, hieu qua
lang xa » dang xay, lang van
lang ha » long ha
cuu tre » cua tre, cau tren, cau treo
va dan » ca dan, va dao, va dau

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

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