Perhaps you should try some spelling variations:
hieu cua » hieu qua, dieu cua, bieu cua
su triet » su tien, ve triet
dang xay » dang van, van xay
thuc va » thuc vat, thuc dan, thuc day
sach ty » sach y, sach tu, sach thu
su sach » so sach, vu sach
lang xa » lang ha, lang van
su viet » so viet
cua am » cua tam, cua nam, cua dam
va dan » ca dan, va dao, va dau
dan va » doan va, dan ca, ban 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 cua am thuc va dan va ((su triet) OR (su viet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ty ((lang xa) OR (dang xay)) hoi. hieu cua am thuc va dan va ((su triet) OR (su viet)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ty ((lang xa) or (dang xay)) hoi. hieu cua am thuc va dan va ((su triet) OR (su viet))".
• Adding a wildcard symbol may retrieve word variants: su sach ty ((lang xa) or (dang xay)) hoi. hieu cua am thuc va dan va ((su triet) OR (su viet))*.