On Legendre’s Work on the Law of Quadratic Reciprocity
ttps://www.jstor.org/stable/10.4169/amer.math.monthly.118.03.210?refreqid=excelsior%3Ad8c24c5d4eaba2fe0cdc5839989ca7e1#metadata_info_tab_contents

Proofs of the Quadratic Reciprocity Law
ttps://www.mathi.uni-heidelberg.de/~flemmermeyer/qrg_proofs.html