Several readers notified me that the tournament in question was not at all a "mysterious" tournament. Moshe Roytman for example notified me of other mentions of it in Davar at the time and in Kandelshine's book about Aloni. Amatzia Avni, Alon Greenefeld and others notified me that the games appear (as I suspected) in Shachmat of 1964. Avni already kindly sent me two sample pages from the report. inally Malkiel Peretz sent me a database of the tournament.
Indeed, it was in fact the top, international, tournament in the traditional Shach Kayit ('Chess Vacation') event in Netanya as (for example) Ma'ariv, 9/6/1964 p. 10, reports, as Mr. Roytman informs me. The two others, incidentally, were a closed tournament for strong Israeli players and an open tournament for amateur players.
So, one may ask indeed: where is the big mystery?
In my defense I merely meant to say that the tournament is a "mysterious" one for the non-Israeli public, not appearing in Chessbase or other sources despite having famous players like Filip and Stahlberg. Indeed this seems to be the case: not only does it not appear in those databases, but I got a request from two different European chess historians for games: one of them (which prompted my original post) heard of the tournament but could find no games, another had noted that the tournament's existence was unknown to him!
All this goes to show what should be an obvious point. Databases and the Internet are all well and good -- but to really understand what happened, one must go back to the original sources. This is especially true when one investigates the history of chess in Israel or in another country whose language is not a major European language, and thus often has material not known to most other chess historians. Indeed, the whole point of this blog is to familiarize the non-Hebrew-speaking public in general, and chess historians in particular, of information that the language barrier (not to mention availability of material) makes hard to find.
In any case, here is the corrected Stahlberg - Blumenfeld game, which Schachmat reported was played in the 9th round:
1. c4 Nf6 2. Nc3 g6 3. d4 Bg7 4. e4 d6 5. Be2 O-O 6. Bg5 c5 7. d5 Qa5 8. Qd2 a6
9. f3 e6 10. g4 exd5 11. cxd5 Re8 12. Nh3 h5 13. Nf2 hxg4 14. fxg4 b5 15. O-O
b4 16. Bxf6 Bxf6 17. Ncd1 Qd8 18. Ne3 Nd7 19. Nc4 Ne5 20. Rab1 Nxc4 21. Bxc4
Bd4 22. Qf4
22... Qh4 23. Qg3 Qxg3+ 24. hxg3 Rxe4 25. b3 Bxg4 26. Rbe1 Rxe1 27. Rxe1
Bf3 28. Kf1 Kg7 White resigns (0-1).