Perhaps you should try some spelling variations:
sach doi » sach hoi, sach moi, sach dao
doi nang » dai nang, hoi nang, voi nang
cam thuc » am thuc, nam thuc, cam thu
hai cau » hai chau, hai chu, hai hau
va danh » va dinh, va dan, va hanh
thuc va » thuc vat, thuc dan, thuc day
su sach » so sach, vu sach
hieu va » lieu va, hieu qua
ma hoi » mai hoi, ma hoa, me hoi
va cam » va cham, va cac, va cao

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

• Performing a fuzzy search may retrieve terms with similar spellings: su sach doi nang ((ma hoi) OR (xa hoi)). hieu va cam thuc va danh ((hai cau) or (lai chau)) treo~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach doi nang ((ma hoi) OR (xa hoi)). hieu va cam thuc va danh ((hai cau) OR (lai chau)) treo.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach doi nang ((ma hoi) OR (xa hoi)). hieu va cam thuc va danh ((hai cau) or (lai chau)) treo".
• Adding a wildcard symbol may retrieve word variants: su sach doi nang ((ma hoi) OR (xa hoi)). hieu va cam thuc va danh ((hai cau) or (lai chau)) treo*.