Perhaps you should try some spelling variations:
cam thuc » am thuc, nam thuc, cam thu
so sach » so sanh, bo sach, co sach
sach ky » sac ky, sach y, sach ty
nang xa » nang x, lang xa, nang ma
tang ma » mang may, tang van
hieu ve » hieu va, hieu van
thuc va » thuc vat, thuc dan, thuc day
va tinh » may tinh
tinh va » tich va, trinh van, trinh vat
cua tre » cua te, cuu tre, cua triet
ve cam » ve cham, ve cac, va cam
va cua » va chua, via cua, ca cua

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 ky ((nang xa) or (tang ma)) hoi. hieu ve cam thuc va tinh va cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach ky ((nang xa) OR (tang ma)) hoi. hieu ve cam thuc va tinh va cua tre.
• Adding a wildcard symbol may retrieve word variants: so sach ky ((nang xa) or (tang ma)) hoi. hieu ve cam thuc va tinh va cua tre*.