Spotlight

When using spotlight what i want to do is just search for items that are only contained inside txt or rtf files.
What do i need to type into spotlight to acheive this. i.e find "txt containing blah blah"

Use the "kind:" command . Unfortunately, I don't think there's a "text" kind, due to the fact that there would be far too many results.

Example:

NewYork Trip kind:image

That will narrow it down to only images, but like I said before, I don't think there's a kind:text command...
:mac: