Perhaps you should try some spelling variations:
vanh tai » van tai, hanh tai, anh tai
thuc dan » thuc hanh, hoc dan, thuc vat
cam thuc » am thuc, nam thuc, cam thu
van dai » vanh dai, van dao, van hai
hieu va » lieu va, hieu qua
sach ky » sach y, sach ty, sach kem
va cam » va cham, va cac, va cao
nang o » nang co, nang ho, nang ro
sac ky » cac ky, sai ky
cua te » cua tu
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: tu ((sach ky) OR (sac ky)) nang o hai. hieu va cam thuc dan ((vanh tai) OR (van dai)) cua te~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu ((sach ky) OR (sac ky)) nang o hai. hieu va cam thuc dan ((vanh tai) or (van dai)) cua te~".
• Adding a wildcard symbol may retrieve word variants: tu ((sach ky) OR (sac ky)) nang o hai. hieu va cam thuc dan ((vanh tai) or (van dai)) cua te*.