There are now four references including Britannica giving the correct date which is getting silly You complain in your edit summary that you can t find them so I ve added quotes to two to help you out After that you re on your own WP SOURCEACCESS has more on this I m happy to concede that Britannica alone mentions the date you offer but without explaining the context so that s one of the sources I ve expanded with a quote specifically mentioning 23 August Russian Wikipedia has 23 14 August 23 forces of the 14th Tank Corps Army of Paulus reached the Volga north of Stalingrad cited from the war diary of Colonel General Franz Haider