This is a site we stumbled across today, it has an epic amount of archived imagery. Set up by (it appears) Dr Chris Mullen: Director of The Culture Archive, Brighton, author of Fortune America, the Visual Achievements of Fortune Magazine, PhD Art History, Brighton.
Once you figure it out, it's an absolute rabbit hole. A great resource where someone has done all the digging for you! Advertising, typography, illustration plus lots more specific reference and resource.