Perhaps you should try some spelling variations:
day hanh » day nhanh, day thanh, dao hanh
thuc day » thuc dan, thuc vat
nam thuc » nam thuoc, am thuc, nam thu
hieu van » hieu va, thien van, lieu va
hanh ca » hanh cac, hanh cat, hanh cua
sach ky » sac ky, sach y, sach kem
hieu ve » hieu va
sach ty » sach y, sach tu, sach thu
cua tre » cua te, cuu tre, cua triet
nang o » nang co, nang ho, nang ro
ca cua » co cua
o hai » co hai, so hai, o lai

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

• If you are trying to use Boolean operators, they must be ALL CAPS: thuat ((sach ky) OR (sach ty)) nang o hai. ((hieu ve) OR (hieu van)) nam thuc day hanh ca cua tre~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thuat ((sach ky) OR (sach ty)) nang o hai. ((hieu ve) or (hieu van)) nam thuc day hanh ca cua tre~".
• Adding a wildcard symbol may retrieve word variants: thuat ((sach ky) OR (sach ty)) nang o hai. ((hieu ve) or (hieu van)) nam thuc day hanh ca cua tre*.