Amalgomation of the American aerospace industry

I recall, several years ago now, a graphic in an issue of Simithsonian Air & Space magazine that illustrated how, between the end of WW2 and present, a dozen or more major aerospace firms merged into the the two major outfits (Boeing and Lockheed) that exist today. I’m wondering if anyone has an extensive back-issue collection who could point me to the issue in which this graphic appeared, or could point me to an online resource that describes this progression?

The Boeing timeline. Lockeed’s in text form. Northrop Grumman’s history summary.