Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
cam thuc » am thuc, nam thuc, cam thu
hanh de » hanh ve, hanh kem
thuc va » thuc vat, thuc dan, thuc day
van cam » van nam, van lam, van cau
sach ky » sach y, sach ty, sach kem
cao hoi » cau hoi, co hoi, cao hoc
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: su ((sach ky) or (sac ky)) nang cao hoi. hieu van cam thuc va ((hanh vi) or (hanh de)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su ((sach ky) OR (sac ky)) nang cao hoi. hieu van cam thuc va ((hanh vi) OR (hanh de)) cua tre.
• Adding a wildcard symbol may retrieve word variants: su ((sach ky) or (sac ky)) nang cao hoi. hieu van cam thuc va ((hanh vi) or (hanh de)) cua tre*.