Perhaps you should try some spelling variations:
cham thuc » nham thuc, pham thuc, tham thuc
hang dau » hang tai
hieu van » hieu va, thien van, hieu ve
tu sach » thu sach, su sach, te sach
sach lo » sach dao, sach doi, sach hoi
thuc va » thuc vat, thuc dan, thuc day
va hanh » van hanh, va thanh, va danh
hanh va » hanh vi
su tien » su kien, su hien, tu tieng

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 lo ((hang dau) or (hang va)) hoi. ((hieu van) OR (lieu va)) cham thuc va hanh va su tien~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach lo ((hang dau) OR (hang va)) hoi. ((hieu van) OR (lieu va)) cham thuc va hanh va su tien.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach lo ((hang dau) or (hang va)) hoi. ((hieu van) OR (lieu va)) cham thuc va hanh va su tien".
• Adding a wildcard symbol may retrieve word variants: tu sach lo ((hang dau) or (hang va)) hoi. ((hieu van) OR (lieu va)) cham thuc va hanh va su tien*.