Great question. If Cessna doesn’t know you may be out of luck.
Try Edward H. Phillips, he’s written a great deal about Cessna.
There is also a Kansas Aviation Musem (I don’t know what the real name is) that does a lot of work on local firms.
Also, here’s a Kansas aviation history website that has a lot of GA content that Phillips writes for:
http://www.wingsoverkansas.com

For what it’s worth, Wiki has a photo of N503CC, which someone there calls the oldest flying Citation.

One of these days, small jets will be considered historic.
Right now, few are in museums…proabably because they’re still worth something as fliers or parts.

The NASM has an early Falcon 20, one of the original FedEX planes and Pima has a nice original Lear 24 (flown in and donated by it orginal owners). And a few ex-USAF JetStars and Sabreliners have been preserved, that’s all I know of.