Came across this interesting site on purring:
Purring.org – The felid purring site
Also, have been looking for this paper again for a while:
Current Biology - The cry embedded within the purr
Our girl Bella does what I assume is the kind of crying/squeeking along with her purr that is being described. My wife noted that she does it only if we are holding her. They call it a "solicitation purr."
