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

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) OR (thuc dan)) hanh di cua viet~.
• 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) OR (thuc dan)) hanh di cua viet.
• 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) OR (thuc dan)) hanh di cua viet".
• Adding a wildcard symbol may retrieve word variants: tu sach hoa lang ma hoi. ((hieu quan) or (hieu qua)) nam ((thuc va) OR (thuc dan)) hanh di cua viet*.