Perhaps you should try some spelling variations:
va triet » va thiet, va trien, ve triet
hieu van » hieu va, thien van, lieu va
vanh dai » van dai, vanh tai, lanh dao
cau thuc » cau truc, cuu thuc, can thuc
van cau » van dau, van hau, van chat
thuc va » thuc vat, thuc dan, thuc day
va vanh » va van, va danh, va hanh
ty nang » ky nang, ty hang, ly nang
tu sach » thu sach, su sach, te sach
dai va » mai va

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: tu sach ((ty nang) OR (ty xang)) ((ma hoa) OR (xa hoi)). hieu van cau thuc va vanh dai va triet~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ((ty nang) OR (ty xang)) ((ma hoa) or (xa hoi)). hieu van cau thuc va vanh dai va triet~".
• Adding a wildcard symbol may retrieve word variants: tu sach ((ty nang) OR (ty xang)) ((ma hoa) or (xa hoi)). hieu van cau thuc va vanh dai va triet*.