Perhaps you should try some spelling variations:
nam thuc » nam thuoc, am thuc, nam thu
cau treo » cau theo, cau tren, cau triet
sach ty » sach y, sach tu, sach thu
tang xa » trang xa, tang ma, tang ha
sach ky » sac ky, sach y, sach kem
hieu va » lieu va, hieu qua
thuc ca » thuc cua, thuc can, thuc cao
dan vai » dan va, dan tai, dan vat
vai cau » va cau, van cau, vai cac
lang xa » lang ha, dang xay, lang van
va nam » van nam, ha nam, va nay
ca dan » cac dan, ca dao

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

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