Perhaps you should try some spelling variations:
cam thuc » am thuc, nam thuc, cam thu
su sach » so sach, vu sach
va tinh » may tinh
thuc va » thuc vat, thuc dan, thuc day
sach ky » sac ky, sach y, sach ty
hieu ve » hieu va, hieu van
tang ma » mang may, tang van
nang xa » nang x, lang xa, nang ma
va cua » va chua, via cua, ma cua
ca cua » co cua
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: su sach ky ((nang xa) or (tang ma)) hoi. hieu ve cam thuc va tinh ((va cua) OR (ca cua)) tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ky ((nang xa) OR (tang ma)) hoi. hieu ve cam thuc va tinh ((va cua) OR (ca cua)) tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ky ((nang xa) or (tang ma)) hoi. hieu ve cam thuc va tinh ((va cua) OR (ca cua)) tre".
• Adding a wildcard symbol may retrieve word variants: su sach ky ((nang xa) or (tang ma)) hoi. hieu ve cam thuc va tinh ((va cua) OR (ca cua)) tre*.