Perhaps you should try some spelling variations:
sach doi » sach hoi, sach moi, sach dao
doi nang » dai nang, hoi nang, voi nang
hieu van » hieu va, thien van, lieu va
hai chu » hai chau, hoi chu, hai chi
hai cau » hai chau, hai hau, hoi cau
lam tuc » lam thuoc, lam truoc, luat tuc
so sach » so sanh, bo sach, co sach
van lam » van nam
tuc va » thuc va, truc va, tuc xa
va dan » ca dan, va dao, va dau
ma hoi » mai hoi, ma hoa, me hoi

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 doi nang ((ma hoi) or (xa hoi)). hieu van lam tuc va dan ((hai cau) OR (hai chu)) triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach doi nang ((ma hoi) OR (xa hoi)). hieu van lam tuc va dan ((hai cau) OR (hai chu)) triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sach doi nang ((ma hoi) or (xa hoi)). hieu van lam tuc va dan ((hai cau) OR (hai chu)) triet".
• Adding a wildcard symbol may retrieve word variants: so sach doi nang ((ma hoi) or (xa hoi)). hieu van lam tuc va dan ((hai cau) OR (hai chu)) triet*.