Perhaps you should try some spelling variations:
doc sach » hoc sach, toc sach, nuoc sach
danh dau » lanh dao, hang dau, danh tu
thai tuc » thai thuc, thai thuy, thai hoc
va triet » va thiet, va trien, ve triet
ty hang » ly hang, ty xang, thi hang
mai hoi » mai khoi, dai hoi, lai hoi
va thai » van thai, va tai, va tham
va danh » va dinh, va dan, va hanh
ly nang » ky nang, ly hang, ly vang
ma hoi » xa hoi, ma hoa, me hoi
tuc va » thuc va, truc va, tuc xa
dau va » dau ve, lau va

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

• Performing a fuzzy search may retrieve terms with similar spellings: doc sach ((ly nang) or (ty hang)) ((ma hoi) or (mai hoi)). lieu va thai tuc va danh dau va triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc sach ((ly nang) OR (ty hang)) ((ma hoi) OR (mai hoi)). lieu va thai tuc va danh dau va triet.
• Adding a wildcard symbol may retrieve word variants: doc sach ((ly nang) or (ty hang)) ((ma hoi) or (mai hoi)). lieu va thai tuc va danh dau va triet*.