I referenced this post here:

>>Where do ideas come from, and who owns them? (Specifically, the Double Diamond model)

short post with lots of comments: https://www.linkedin.com/posts/antlerboy_doublediamond-designthinking-servicedesign-activity-6795601313569882112-pEL_

full (short) research here: https://stream.syscoi.com/2021/05/05/the-double-diamond-as-an-example-of-some-challenges-of-attribution-in-the-history-of-ideas/