Perhaps you should try some spelling variations:
va triet » va trien, ve triet, cua triet
nam thuc » nam thuoc, am thuc, nam thu
so sach » so sanh, bo sach, co sach
hanh va » hang va, hanh vi
va hanh » van hanh, va thanh, va danh
thuc va » thuc vat, thuc dan, thuc day
hieu he » hieu ve, hiem he, hieu le
ly vang » ly hang, ly van, ly quang
ly nang » ky nang, ly hang, ly quang
he nam » ha nam, nghe nam
ma hoi » mai hoi, xa hoi, ma hoa
thiet » thieu

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

• Performing a fuzzy search may retrieve terms with similar spellings: so sach ((ly nang) OR (ly vang)) ma hoi. hieu he nam thuc va hanh va ((va triet) or (va thiet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach ((ly nang) OR (ly vang)) ma hoi. hieu he nam thuc va hanh va ((va triet) OR (va thiet)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sach ((ly nang) OR (ly vang)) ma hoi. hieu he nam thuc va hanh va ((va triet) or (va thiet))".
• Adding a wildcard symbol may retrieve word variants: so sach ((ly nang) OR (ly vang)) ma hoi. hieu he nam thuc va hanh va ((va triet) or (va thiet))*.