Perhaps you should try some spelling variations:
hieu quan » lieu quan, thien quan, lien quan
hoa lang » hoa dan, hoa van
cua viet » ca viet, hoa viet, cua dieu
sach hoa » sach ha, sach hoi, bach hoa
nam thuc » nam thuoc, am thuc, nam thu
tu sach » thu sach, su sach, te sach
hanh di » hanh vi, hanh de, hang di
lang ma » lang mai, lang man, lang ha
thuc va » thuc vat, thuc dan, thuc day
va hanh » van hanh, va thanh, va danh
ma hoi » mai hoi, xa hoi, ma hoa

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach hoa lang ma hoi. ((hieu quan) or (hieu qua)) nam thuc va hanh di ((cua viet) OR (cua vat))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach hoa lang ma hoi. ((hieu quan) OR (hieu qua)) nam thuc va hanh di ((cua viet) OR (cua vat)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach hoa lang ma hoi. ((hieu quan) or (hieu qua)) nam thuc va hanh di ((cua viet) OR (cua vat))".
• Adding a wildcard symbol may retrieve word variants: tu sach hoa lang ma hoi. ((hieu quan) or (hieu qua)) nam thuc va hanh di ((cua viet) OR (cua vat))*.