SchwaigerJ. “Connections Between the Completion of Normed Spaces over Non-Archimedean Fields and the Stability of the Cauchy Equation”. Annales Mathematicae Silesianae, Vol. 34, no. 1, May 2020, pp. 151-63, https://journals.us.edu.pl/index.php/AMSIL/article/view/13640.