Perhaps you should try some spelling variations:
cam thuc » am thuc, nam thuc, cam thu
hieu van » hieu va, thien van, lieu va
sach ky » sach y, sach ty, sach kem
hanh di » hanh vi, hanh de, hang di
va hanh » van hanh, va thanh, va danh
thuc va » thuc vat, thuc dan, thuc day
van cam » van nam, van lam, van cau
cua tre » cua te, cuu tre, cua triet
ma hoi » mai hoi, ma hoa, me hoi
sac ky » cac ky, sai ky
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: su ((sach ky) or (sac ky)) nang ((ma hoi) OR (xa hoi)). hieu van cam thuc va hanh di cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su ((sach ky) OR (sac ky)) nang ((ma hoi) OR (xa hoi)). hieu van cam thuc va hanh di cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su ((sach ky) or (sac ky)) nang ((ma hoi) OR (xa hoi)). hieu van cam thuc va hanh di cua tre".
• Adding a wildcard symbol may retrieve word variants: su ((sach ky) or (sac ky)) nang ((ma hoi) OR (xa hoi)). hieu van cam thuc va hanh di cua tre*.