You're correct on the face of it. However it would take more research to get the entire story.
* Example, to find out whether the original author gave permission for his work to be included among other works uncredited.
* Example, did the presumed guilty party ask an assistant to find an article about Zeta converters, which then found its way into a collection of generic app notes (being that it's an app note), uncredited?
* Example, is there an assistant (colleague, etc.) who has sinister motives? (Rather than the presumed guilty party?)
* Example, does Analog Devices hold the legal copyright, and gives general permission for the app note to be copied-and-pasted, with advice to include its logo, or its brand, etc., somewhere in the reprint?
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Each of the authors involved has a great deal to lose. For someone that's prominent in his field it's unlikely he'd knowingly engage in intellectual theft.
I'm not sure about the best way to follow up on your suspicions, which party to contact first, what details to give, what questions to present.