Uwe Hassler, Mehdi Hosseinkouchack
In this note, we offer a historical perspective on solutions of the Basel
problem. In particular, we have a closer look at some of the less famous results
by Euler E41 and provide a review of a selection of the assemblage of earlier
proofs. Moreover, we show how to generate further proofs using
Karhunen-Lo\`{e}ve expansions of stochastic processes.