The Star Trek (1966) book, "Rules of Engagement", that Sheldon is reading on the couch as Missy enters was not published until September of 2000. As the Cooper twins are no more than 13-14 in this season, that would place the events of this episode somewhere around the year 1993 at the latest.
Sheldon's voice over refers to "the Ukraine". The name of the country is just "Ukraine" (much how you would not refer to "The France"). Someone like Sheldon would not have made this error.