Perhaps you should try some spelling variations:
thuc dan » thuc hanh, hoc dan, thuc vat
vanh tai » van tai, hanh tai, anh tai
cam thuc » am thuc, nam thuc, cam thu
tu sach » thu sach, su sach, te sach
hieu va » lieu va, hieu qua
sach ky » sac ky, sach y, sach ty
va cam » va cham, va cac, va cao
co hai » co dai, co hoi, so hai
cua te » cua tu
o hai » so hai, o lai, _ hai

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) OR (co hai)). hieu va cam thuc dan ((vanh tai) OR (lanh dao)) cua te~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky nang ((o hai) OR (co hai)). hieu va cam thuc dan ((vanh tai) or (lanh dao)) cua te~".
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang ((o hai) OR (co hai)). hieu va cam thuc dan ((vanh tai) or (lanh dao)) cua te*.