Perhaps you should try some spelling variations:
nam thuc » nam thuoc, am thuc, nam thu
dang xay » dang van, van xay
su sach » so sach, vu sach
cua tre » cua te, cua triet, dua tren
thuc va » thuc vat, thuc dan, thuc day
sach ty » sach y, sach tu, sach thu
qua nam » quan nam, cua nam, quang nam
lang xa » lang ha, lang van
cuu tre » cau tren, cau treo
va dao » ca dao
dao vi » dao voi, dao ve, dao va

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