Wes Stewart wrote:

Unless I'm mistaken, the copyright would have had to been renewed to
remain in effect.

According to this link:

http://www.scils.rutgers.edu/~lesk/copyrenew.html

it was not.

Thanks for the URL - it looks like it'll come in handy. Unfortunately,
the fourth sentence on that page is "This file does not contain listings
for music, movies, or periodicals." The BLE paper was published in the
_Proceedings of the IRE_, a periodical.

Roy Lewallen, W7EL