|Z truth 000000001: <Ziryab> the score given here (with 12.Raxc1) matches the tb:|
<XVIII первенство ссср по шахматам - <С. Флор--Т. Петросян> (R9) G-81 p163>
A fuller ref to Pachman would have saved me a little time - given I was flipping through, page by page, trying to find the Flohr game. (It wasn't in the game index.)
A bit tedious, so I soondecided to do a google search - which yielded the source directly!
Oh the irony! (aka OCR wins again)
<ziryab>'s ref comes from a note in <Sakellarpoulos--Boleslavski (Helsinki 1952) p18> for 10...B-R3!! (a bit exuberant) concerning good vs bad bishops. And yes, Pachman seems to suggest Flohr played 12.Nxc5.
Perhaps in a different game with Petrosian (given no particulars of the sidenote game is given other than the players)?
Let's do a tree search with SCID to see...
OK, it seems Pachman got it wrong. The earliest KID with this position:
click for larger view
is <Petrosian--Geller (Moscow 1949)>, according to <Millbase>.
Petrosian was the one to play 12.Nxc5, next year, Flohr played 12.Raxc1 for the first time.
Side note: 12.Raxc1 seems more natural to me, and is far and away the dominant continuation in <Millbase>. But analysis seems to suggest (in agreement with Pachman(?)), that White has full flexibility to take with either rook, or to even play as Petrosian did in 1949.