Perhaps you should try some spelling variations:
cua triet » cua viet, su triet, va triet
nam thuc » nam thuoc, am thuc, nam thu
dang xay » dang van, van xay
cua tre » cua te, cuu tre, dua tren
thuc va » thuc vat, thuc dan, thuc day
sach ty » sach y, sach tu, sach thu
su sach » so sach, vu sach
nang xa » nang x, lang xa, nang ma
qua nam » quan nam, cua nam, quang nam
va dan » ca dan, va dao, va dau
dan vi » doan vi, don vi, dan 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 ((nang xa) or (dang xay)) hoi. hieu qua nam thuc va dan vi ((cua tre) OR (cua triet))~.
• 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 vi ((cua tre) OR (cua triet)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ty ((nang xa) or (dang xay)) hoi. hieu qua nam thuc va dan vi ((cua tre) OR (cua triet))".
• Adding a wildcard symbol may retrieve word variants: su sach ty ((nang xa) or (dang xay)) hoi. hieu qua nam thuc va dan vi ((cua tre) OR (cua triet))*.