Copyright agreements of certain publishers such as Springer and IEEE request that if an author archives a published paper on his/her web page, then a link to the publisher's site must be provided, e.g., "The final publication is available at [Web site of the publisher]". Is this request a legally valid one according to German / US legislation? Why / why not?
An aside: this is probably a very standard question, and someone in the community is very likely to have already seeked legal advice on that. I would expect that at least the legal departments of huge universities know the answer.