Perhaps you should try some spelling variations:
nam thuc » nam thuoc, am thuc, nam thu
hieu cua » hieu qua, dieu cua, bieu cua
dang xay » dang van, van xay
su sach » so sach, vu sach
sach ty » sach y, sach tu, sach thu
cua nam » cua tam, cua ngan, cua nhan
lang xa » lang ha, lang van
va dan » ca dan, va dau, va dap
va dao » ca dao
va cua » va chua, via cua, ca cua
cua te » cua tu

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

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