Perhaps you should try some spelling variations:
sach kem » hanh kem
thuc dan » thuc hanh, hoc dan, thuc vat
thuc day » thuc vat
hieu ve » hieu va, hieu van
ve nham » ve nha, ve cham
cao hoi » cau hoi, co hoi, cao hoc
hanh di » hanh vi, hanh de, hang di
cua tre » cua te, cuu tre, cua triet
di cua » dai cua, doi cua, de cua

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: thu ((sach kem) or (sach y)) nang cao hoi. hieu ve nham ((thuc day) OR (thuc dan)) hanh di cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu ((sach kem) OR (sach y)) nang cao hoi. hieu ve nham ((thuc day) OR (thuc dan)) hanh di cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu ((sach kem) or (sach y)) nang cao hoi. hieu ve nham ((thuc day) OR (thuc dan)) hanh di cua tre".
• Adding a wildcard symbol may retrieve word variants: thu ((sach kem) or (sach y)) nang cao hoi. hieu ve nham ((thuc day) OR (thuc dan)) hanh di cua tre*.