  In the article "Universal Densities Exist for Every Finite Reference Measure"
(IEEE Trans. Inform. Theory, vol. 69, no. 8, pp. 5277--5288, 2023) we neglected
to mention relevant contributions of Boris Ryabko. We cited a source by him
that contains a construction of the universal density that we claimed to be our
own invention without checking the source after drafting the article. Our
article was motivated by a preprint by Feutrill and Roughan, about which we had
learned when reviewing the PhD thesis by Andrew Feutrill. Whereas we were not
allowed to contact Feutrill and Roughan besides the review form, we developed
some ideas of theirs further, ignoring that we stepped into the area previously
researched by Ryabko. Our published results exceed those by Ryabko but the
article should have been refocused to report Ryabko's contributions. In this
note, we detail our citation mistakes.
