Perhaps you should try some spelling variations:
dang xay » dang van, van xay
nam thuc » nam thuoc, am thuc, nam thu
su sach » so sach, vu sach
sach ty » sach y, sach tu, sach thu
nang xa » nang x, lang xa, nang ma
qua nam » quan nam, cua nam, quang nam
thuc va » thuc vat, thuc dan, thuc day
cua tre » cua te, cuu tre, cua triet
va dan » ca dan, va dao, va dau
dan di » danh di, dan da, dan de
di cua » dai cua, doi cua, de cua

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 ((nang xa) or (dang xay)) hoi. hieu qua nam thuc va dan di cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ty ((nang xa) OR (dang xay)) hoi. hieu qua nam thuc va dan di cua tre.
• Adding a wildcard symbol may retrieve word variants: su sach ty ((nang xa) or (dang xay)) hoi. hieu qua nam thuc va dan di cua tre*.