Perhaps you should try some spelling variations:
cam thuc » am thuc, nam thuc, cam thu
van nang » van quang, van ban, van dong
cua viet » hoa viet, cua vat, cua dieu
hanh vai » hanh vi, hanh va, hanh tai
van hanh » van thanh, ban hanh, van anh
thuc van » thuc vat, thuc dan, thuc va
sach van » sach han, sach va, bach van
so sach » so sanh, bo sach, co sach
ca viet » va viet, co viet, hoa viet
hieu ve » hieu va, hieu van
lai roi » lai hoi, loi roi
mai hoi » mai khoi, dai hoi, lai hoi
ve cam » ve cham, ve cac, va cam

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 van nang ((mai hoi) or (lai roi)). hieu ve cam thuc van hanh vai ((cua viet) OR (ca viet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach van nang ((mai hoi) OR (lai roi)). hieu ve cam thuc van hanh vai ((cua viet) OR (ca viet)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sach van nang ((mai hoi) or (lai roi)). hieu ve cam thuc van hanh vai ((cua viet) OR (ca viet))".
• Adding a wildcard symbol may retrieve word variants: so sach van nang ((mai hoi) or (lai roi)). hieu ve cam thuc van hanh vai ((cua viet) OR (ca viet))*.