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