Perhaps you should try some spelling variations:
ve triet » va trien
nam thuc » nam thuoc, am thuc, nam thu
nang mai » nang ma, lang mai, nang cai
su triet » su viet, su tien
nang tai » hang tai, tang tai, sang tai
va hanh » van hanh, va thanh, va danh
thuc va » thuc vat, thuc dan, thuc day
so sach » so sanh, bo sach, co sach
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 y ((nang mai) OR (nang tai)) hoi. hieu ve nam thuc va hanh vi ((su triet) OR (ve triet))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sach y ((nang mai) OR (nang tai)) hoi. hieu ve nam thuc va hanh vi ((su triet) or (ve triet))~".
• Adding a wildcard symbol may retrieve word variants: so sach y ((nang mai) OR (nang tai)) hoi. hieu ve nam thuc va hanh vi ((su triet) or (ve triet))*.