Perhaps you should try some spelling variations:
ve triet » va trien
nam thuc » nam thuoc, am thuc, nam thu
su triet » su viet, su tien
van hang » van khang, van hoang, van thang
thuc van » thuc vat, thuc dan, thuc va
so sach » so sanh, bo sach, co sach
sach ky » sac ky, sach y, sach ty
lai hoi » dai hoi, lai hoa, lai roi
mai hoi » mai khoi, dai hoi, mai doi
hieu ve » hieu va, hieu van
ve nam » he nam, va nam, le nam

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

• If you are trying to use Boolean operators, they must be ALL CAPS: so sach ky nang ((mai hoi) OR (lai hoi)). hieu ve nam thuc van hang va ((su triet) OR (ve triet))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sach ky nang ((mai hoi) OR (lai hoi)). hieu ve nam thuc van hang va ((su triet) or (ve triet))~".
• Adding a wildcard symbol may retrieve word variants: so sach ky nang ((mai hoi) OR (lai hoi)). hieu ve nam thuc van hang va ((su triet) or (ve triet))*.