Perhaps you should try some spelling variations:
cam thuc » am thuc, nam thuc, cam thu
tinh nha » trinh nha, tinh ha, hinh nha
hieu van » thien van, lieu va, hieu ve
su sach » so sach, vu sach
hieu va » lieu va, hieu qua
nha cua » nhat cua, nhan cua, nghia cua
va tinh » may tinh
thuc va » thuc vat, thuc dan, thuc day
cua tre » cua te, cuu tre, cua triet
nang xa » nang x, lang xa, mang xa
nang ma » tang ma, sang ma, nang cao

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 y ((nang xa) or (nang ma)) hoi. ((hieu van) OR (hieu va)) cam thuc va tinh nha cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach y ((nang xa) OR (nang ma)) hoi. ((hieu van) OR (hieu va)) cam thuc va tinh nha cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach y ((nang xa) or (nang ma)) hoi. ((hieu van) OR (hieu va)) cam thuc va tinh nha cua tre".
• Adding a wildcard symbol may retrieve word variants: su sach y ((nang xa) or (nang ma)) hoi. ((hieu van) OR (hieu va)) cam thuc va tinh nha cua tre*.