First edition of the Great Soviet Encyclopedia, 65 volumes issued between 1926-1947.
The 1920s saw the publication of the first 16 volumes (list by date).
Torrent attached as zip-file. When you launch the torrent, you have the option to select particular volumes for download (in total the size is almost 12 GB).
In case it doesn't work, here's the site where I took it from (requires sign-up): http://kinozal.tv/details.php?id=1200774 (Second and third edition linked there too)
The volumes are OCR'd, so you can copy-paste texts into an e-translation site.
Volume 4, for example contains such entries as 'Afghanistan', 'Atom', 'Butterfly', 'Bakunin', 'Balance of payments' (written by Dvolajtskij), 'Banknote', 'Barricade'.