Perhaps you should try some spelling variations:
biet nghi » biet nguoi, viet nghin, biet noi
kien nghi » kien chi, kien noi
nhung bo » nhung bi, nhung bai, nhung don
khoa hoc » hoa hoc
tu sach » thu sach, te sach, tu cach
su sach » so sach, vu sach
bo oc » bo uoc, bo o
oc vi » hoc vi, doc vi

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((tu sach) or (su sach)) khoa hoc ((kien nghi) or (biet nghi)) cua ets : nhung bo oc vi đai~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (su sach)) khoa hoc ((kien nghi) OR (biet nghi)) cua ets : nhung bo oc vi đai.
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (su sach)) khoa hoc ((kien nghi) or (biet nghi)) cua ets : nhung bo oc vi đai*.