Karpova: This game is from the Pre-tournament (<Vorturnier>) of the Trebitsch Memorial 1936. Lenner represented Austria at the Unofficial Chess Olympiad in Munich, 1936: http://www.olimpbase.org/1936x/1936...Annotations by Rudolf Spielmann (condensed):
6...Nbd7 <Alternatively Nc6 to enforce e5.>
11.Rae1 <Why not Rfe1?>
11...b6 <Before the Queen's ♘ goes to g6, the Queen's side shall be sealed off. But this was not necessary, as Reischer's fear of d5 was unjustified.>
15...Rf8 <To be prepared for the thrust f2-f4-f5. The ♘f6 shall go to e8 and then folowed up with f5.>
17.g4 <? Looks very good but is in reality forcefully refuted by Black. Lenner wanted to circumvent the complications of f4. The text move shall prevent f5 and White plans to intrude by Ng1-e2-g3-f5 himself.>
18...h5 <! The attack is commenced with an energetic ♙ sacrifice and Lenner gets into the dangerous operation.>
23.e5 <The counter chance! But Reischer is not intimidated.>
24...f5 <! Looks risky but is well calculated, as Black comes first.>
27.Nf1 <White wants to "reconcile" Black with a piece sacrifice, but she is "irreconcilable". If, for example, 27.f3 then 27...Qg3+ 28.Kh1 gxh3 29.Bf1 Qxe1.>
32.Nxf5 <? A blunder in a losing position. Best is 32.Nxg2 after which 32...Qh6 wins, preventing the ♘ intrusion on f4.>
Source: Pages 329-330 of the November 1936 'Wiener Schachzeitung'