Perhaps you should try some spelling variations:
sach kem » hanh kem
hieu cao » chieu cao, hieu cac, hieu ca
thuc dan » thuc hanh, hoc dan, thuc vat
sinh dai » sinh thai, si dai, sinh vat
nang xa » nang x, lang xa, nang ma
thuc va » thuc vat, thuc day
cua tre » cua te, cuu tre, cua triet
sac ky » cac ky, sai ky

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 (sac ky)) nang xa hoi. hieu cao chat ((thuc va) OR (thuc dan)) sinh dai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu ((sach kem) OR (sac ky)) nang xa hoi. hieu cao chat ((thuc va) OR (thuc dan)) sinh dai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu ((sach kem) or (sac ky)) nang xa hoi. hieu cao chat ((thuc va) OR (thuc dan)) sinh dai cua tre".
• Adding a wildcard symbol may retrieve word variants: thu ((sach kem) or (sac ky)) nang xa hoi. hieu cao chat ((thuc va) OR (thuc dan)) sinh dai cua tre*.