Perhaps you should try some spelling variations:
hieu quang » thieu quang, hieu quan, hieu qua
dang xay » dang van, van xay
nam thuc » nam thuoc, am thuc, nam thu
so sach » so sanh, bo sach, co sach
lang xa » lang ha, lang van
thuc va » thuc vat, thuc dan, thuc day
dan vat » dang vat, van vat, dan va
vat cua » mat cua, bat cua, dat cua
cua tre » cua te, cuu tre, cua triet
va dan » ca dan, va dao, va dau

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

• Performing a fuzzy search may retrieve terms with similar spellings: so sach y ((lang xa) or (dang xay)) hoi. hieu quang nam thuc va dan vat cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach y ((lang xa) OR (dang xay)) hoi. hieu quang nam thuc va dan vat cua tre.
• Adding a wildcard symbol may retrieve word variants: so sach y ((lang xa) or (dang xay)) hoi. hieu quang nam thuc va dan vat cua tre*.