Perhaps you should try some spelling variations:
day thanh » dao thanh, dat thanh, da thanh
thanh va » thanh van, hanh va, thanh ha
thuc day » thuc dan, thuc vat
hieu van » hieu va, thien van, lieu va
cua tre » cua te, cuu tre, cua triet
hieu ve » hieu va
sang ma » tang ma, nang ma, sang tao
ky sang » ky nang, ky dang, ky tang
ma hoi » mai hoi, xa hoi, ma hoa
tu bai » tu ban, tu bat, te bai
va cua » va chua, via cua, ca cua
tu cai » tu cac, tu can, tu cay

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: ((tu cai) OR (tu bai)) ky sang ma hoi. ((hieu ve) OR (hieu van)) am thuc day thanh va cua tre~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu cai) or (tu bai)) ky sang ma hoi. ((hieu ve) OR (hieu van)) am thuc day thanh va cua tre~".
• Adding a wildcard symbol may retrieve word variants: ((tu cai) or (tu bai)) ky sang ma hoi. ((hieu ve) OR (hieu van)) am thuc day thanh va cua tre*.