|Source: Shachmat, June-July 1964, Vol. 2 no. 11-12 (23-24), back cover|
I should have known better; I fell into the trap of believing Chessbase and similar online / computer sources are reliable. They are indeed, when it comes to recent (ca. 1990-) tournaments and international events, but not at all when it comes to smaller, historical events that were mostly reported in non-European (or American) sources. This is why Jeremy Gaige's and other archivists' work, such as the multi-volume Chess Tournaments Crosstable (which, alas, I do not have access to) and Chess Personalia are indispensable.