Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
nam thuc » nam thuoc, am thuc, nam thu
cau treo » cau theo, cau tren, cau triet
lang ha » long ha
hieu va » lieu va, hieu qua
lang xa » dang xay, lang van
va dan » va dao, va dau, va dap
ca dan » cac dan, ca dao
va cau » van cau, va cac, va dau
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 y ((lang xa) or (lang ha)) hoi. hieu va nam thuc ((va dan) OR (ca dan)) va cau treo~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach y ((lang xa) OR (lang ha)) hoi. hieu va nam thuc ((va dan) OR (ca dan)) va cau treo.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach y ((lang xa) or (lang ha)) hoi. hieu va nam thuc ((va dan) OR (ca dan)) va cau treo".
• Adding a wildcard symbol may retrieve word variants: toc sach y ((lang xa) or (lang ha)) hoi. hieu va nam thuc ((va dan) OR (ca dan)) va cau treo*.