Perhaps you should try some spelling variations:
vat hanh » vat thanh, van hanh, va hanh
nam thuc » nam thuoc, am thuc, nam thu
sach ky » sach y, sach ty, sach kem
hanh di » hanh vi, hanh de, hang di
hieu ve » hieu va, hieu van
mai hoi » mai khoi, dai hoi, lai hoi
cua tre » cua te, cuu tre, cua triet
ma hoi » xa hoi, ma hoa, me hoi
ve nam » he nam, va nam, le nam
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 (mai hoi)). hieu ve nam thuc vat 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 (mai hoi)). hieu ve nam thuc vat 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 (mai hoi)). hieu ve nam thuc vat hanh di cua tre".
• Adding a wildcard symbol may retrieve word variants: su ((sach ky) or (sac ky)) nang ((ma hoi) OR (mai hoi)). hieu ve nam thuc vat hanh di cua tre*.