How does one choose which articles to cite for a very broad sentence?
Either none at all if you can assume that the most likely audience of your publication is aware of that as if it was a basic fact of life.
Or recent reviews that provide a wide overview of Gaussians used in mathematics and/or statistics.
I searched for TITLE: (Gaussian) AND DOCUMENT TYPES: (Review) AND YEAR PUBLISHED: (2015-2021) in Web of Science. The query led to 56 results, many of which have accrued considerable citations and thematize mathematical or statistical issues. Perhaps you could do a similar search and pick some suitable papers to cite.